Monday, July 06, 2020

vCenter Server Appliance - Update installation is in progress

A few days ago, I have updated my home-lab VCSA vCenter Server 7.0 GA (15952498) to vCenter Server 7.0.0a (16189094). Everything seemed ok from the vCenter (vSphere Client) perspective. I was seeing there vCenter build 16189207, which is obviously VCSA 16189094.

The only problem I had was the fact, that I was not able to log in to VCSA VAMI.

After user authentication into VAMI, I was getting a message ... "Update installation is in progress". During the problem isolation, I tested the REST API and was getting the same message through Appliance REST API.

To be honest, I had no idea, how to check VCSA update status and move it forward, therefore I did the log files troubleshooting.

In /var/log/vmware/applmgmt/vami.log I had regularly repeating messages... "Executing VMware vCenter Server SNMP post upgrade actions..."

The next step was parsing PatchRunner.log. There was nothing remarkable except info about the patch stageDir located at "/storage/core/software-update/updates/" where i had two empty directories and file "patch_phase_context.json"

Normally, the directory /storage/core/software-update/updates/ is empty, however I have there still subdirectory with patch … /storage/core/software-update/updates/

I tried to delete the whole directory /storage/core/software-update/updates/ but it did not help.

It seemed, that post-upgrade actions (specifically VMware vCenter Server SNMP) cannot finish.

I HAD NO IDEA ... I WAS STUCK ... the next step was the research on the internal VMware slack channel. I have not found anything, therefore asked for help. In a few days, somebody else had the same issue in his home lab and he got the tip from VMware Engineering guys.

The trick was in file /etc/applmgmt/appliance/software_update_state.conf

I had there the following content

    "state": "INSTALL_IN_PROGRESS",
    "version": "",
    "latest_query_time": "2020-06-12T17:30:46Z",
    "operation_id": "/storage/core/software-update/install_operation"

so the trick was to change the content into

    "state": "UP_TO_DATE"

After the change, I was able to log in to VAMI and use it as usual. Well, almost as usual.
I realized, that I was not able to start another update as buttons [STAGE ONLY] and [STAGE AND INSTALL] are greyed out.

Nevertheless, this is only GUI problem and VCSA CLI update procedure works like a charm, so the update can be done through SSH session and command software-packages install --url or software-packages install --iso

Another positive thing is, that I was able to perform vCenter native backup, so if needed, I have the option to do a VCSA backup and restore, which would probably solve this cosmetic GUI issue.

Disclaimer: This exercise was done in my home lab. If you will experience a similar issue in a production system, please, contact VMware support before any changes in VCSA.

Monday, June 22, 2020

What's new in VxRail 7.0

This is a very short blog post about VxRail 7.0 which has been launched today. First of all, VxRail naming has been aligned with vSphere versioning, hence VxRail 7.0. Here is the summary of the announcement:

  • VxRail 7.0 includes the vSphere 7.0 and vSAN 7.0
  • Customers can now run vSphere Kubernetes on the Dell Tech Cloud Platform, VMware Cloud Foundation 4.0 on VxRail 7.0.
  • With a more accessible Consolidated Architecture, Dell Technologies Cloud Platform can now be deployed starting with a 4-node configuration.
  • Brand-new Dell EMC VxRail D Series – the most extreme yet. The D560/D560F is a ruggedized, durable platform that delivers the full power of VxRail for workloads at the edge, in challenging environments, or for space-constrained areas.
  • Even more platform flexibility with the new VxRail E Series model based on, for the first time, AMD EPYC processors.
  • The single socket, 1U nodes offer dual-socket performance making them ideal platforms for desktop VDI, analytics, and computer-aided design.
  • Enhanced operational benefits with new automation and self-service features enabling customers to schedule and run upgrade health checks in advance of upgrades with VxRail HCI System Software.
  • The addition of Intel® Optane™ DC Persistent Memory to the E560 and P570 platforms offers high performance and significantly increased memory capacity with data persistence.
  • The latest NVIDIA® Quadro RTX™ 6000 and 8000 GPUs to the V570F bringing the most significant advancement in computer graphics in over a decade to professional workflows.
If you were unable to attend the event, you can always visit the VxRail event page, where you can watch it OnDemand!

Monday, May 11, 2020

Undocumented HA Advanced Option - das.restartVmsWithoutResourceChecks

Some time ago, a colleague of mine (@stan_jurena) was challenged by one VMware customer who experienced APD (All Path Down) storage situation in the whole HA Cluster and he expected that VMs will be killed by VMware Hypervisor (ESXi) because of HA Cluster APD response setting "Power off and restart VMs - Aggressive restart policy". To be honest, I had the same expectation. However, after the discussion with VMware engineering, we have been told, that the primary role of HA Cluster is to keep VMs up and running, so "Aggressive restart policy" will restart VM only in certain conditions which are much better described in vSphere Client 7 UI. See the screenshot below.

APD Aggressive restart policy
A VM will be powered off, If HA determines the VM can be restarted on a different host, or if HA cannot detect the resources on other hosts because of network connectivity loss (network partition).

So, what it means? Aggressive restart policy is the same as Conservative but extended for the situation when there is network partitioning. This can be helpful in situations when you have IP storage and experience IP network issues but it does not help in a situation when you have dedicated Fibre Channel SAN and the storage is not available for the whole vSphere Cluster.

We explained to VMware engineering, that there are situations when it is much better to kill all VMs than keep compute (VMs) running without available storage. Based on these discussions, there was created a Feature Request, which was internally named as "super aggressive option" APD. I'm happy to see, that it was implemented and released in vSphere 7 as vSphere advanced option
das.restartVmsWithoutResourceChecks = false (default) / true (super aggressive)
I think this advanced option will be very useful for infrastructure architects / technical designers who will have a good justification to use this advanced option. Here are my typical justifications
  • When the storage subsystem is unavailable for some time, Linux operating system switch file system to Read-Only mode which has a negative impact on running applications. Such a situation typically leads to server restart anyway.
  • When you have an OS/Application clustering solution (for example MSCS) on top of vSphere clustering, having one Application node on one vSphere cluster and another Application node on different vSphere cluster, you prefer to kill VM (App Node) on the problematic cluster (without available storage) to fail-over to App Node (VM) running on the healthy cluster.
Hope this makes sense.

Please leave the comment if you will find this advanced option useful. VMware Engineering might consider adding this option into GUI, based vSphere architects / technical designers' feedback.

  • Duncan Epping wrote the blog post about it here.
  • For other "Advanced configuration options for VMware High Availability in vSphere 5.x and 6.x" check VMware KB 2033250.

Friday, May 08, 2020

CPU capacity planning and sizing

During infrastructure capacity planning and sizing, the technical designer has to calculate CPU, RAM, Storage, and Network resource requirements. Recently, I had an interesting discussion with my colleagues on how to estimate CPU requirements for application workload.

Each computer application requires some CPU resources for computational tasks and additional resources for I/O tasks. It is obvious that the computational tasks require CPU cycles, however, it is not so obvious that there are CPU cycles associated also with I/O. In other words, each I/O requires some CPU resources. It does not matter if it is memory, storage, or network I/O.

For example, a generally accepted rule of thumb in the networking is that
1 Hertz of CPU processing is required to send or receive 1 bit/s of TCP/IP.
[Source: VMware vSphere 6.5 Host Resources Deep Dive]

This would mean 2.5Gb/s would require ~ 2.5Ghz CPU, thus ~ 100% of one CPU Core @ 2.5 GHz.

It would be nice to have a similar rule of thumb for storage I/O. I did quick research (googling) but was not able to find any information about CPU requirements for storage I/O.  I did a quick test in my home lab and start the synthetic random workload (4KB I/O) on 4vCPU VM on ESXi host having CPU at 2 GHz, where I was able to see 5,000 IOPS with CPU utilization 8.5%. This would mean one 4KB I/O requires 136 Hz.

4KB I/O on 4x vCPU VM with pCPU @ 2 GHz 
I did another test with 512 B I/O where 1 IOPS requires 114 Hz.
And for 64KB I/O size, 1 IOPS requires 161 Hz.

0.5 KB I/O => 512 Bytes I/O (4,096 bits) = 114 Hz
4 KB I/O => 4,096 Bytes I/O (32,768 bits) = 136 Hz
64 KB I/O => 65,536 Bytes I/O (52,4288 bits) = 161 Hz

Based on my observations, it is difficult to define the rule of thumb for 1 Bit/s or Byte/s but rather I would define CPU (Hz) requirements for 1 storage I/O.

Based on multiple assessments of real datacenter environments, I would say that typical average storage I/O size is around 40-50 KB, therefore here is my rule of thumb
1 Storage I/O requires ~ 150 Hz of CPU processing
This would mean 10,000 IOPS would require ~ 1.5 GHz, thus 60% of one CPU Core @ 2.5 GHz.

Please, be aware that this is a very simplified calculation but clearly shows that storage workload is always associated with CPU requirements and it can help with capacity planning and infrastructure sizing.

What do you think about this calculation?
Do you observe different numbers?
Would you calculate it differently?
You can leave the comment below the article.

Sunday, May 03, 2020

vSphere 7 - Storage Requirements for the vCenter Server Appliance

I have upgraded vSphere in my home lab and realized that VCSA 7.0 storage requirements increased significantly.

Here are the requirements of vCenter Server Appliance 6.7

Here are the requirements of vCenter Server Appliance 7.0

You can see the difference by yourself. VCSA 7.0 requires roughly 30%-60% more storage than VCSA 6.7. It is good to know it especially for home labs where hardware resources are limited or during logical designs of new environments where you do some math calculation to plan hardware requirements.

Monday, April 20, 2020

What's New in vSAN 7

vSAN 7.0 introduces the following new features and enhancements.

vSphere Lifecycle Manager (vLCM).

vLCM enables simplified, consistent lifecycle management for your ESXi hosts. It uses a desired-state model that provides lifecycle management for the hypervisor and the full stack of drivers and firmware. vLCM reduces the effort to monitor compliance for individual components and helps maintain a consistent state for the entire cluster. In vSAN 7.0, this solution supports Dell and HPE ReadyNodes.

Integrated File Services. 

vSAN native File Service delivers the ability to leverage vSAN clusters to create and present NFS (v4.1 and v3) file shares. vSAN File Service extends vSAN capabilities to files, including availability, security, storage efficiency, and operations management.

Native support for NVMe hotplug.

This feature delivers a consistent way of servicing NVMe devices and provides operational efficiency for select OEM drives.

I/O redirect based on capacity imbalance with stretched clusters.

vSAN redirects all VM I/O from a capacity-strained site to the other site, until the capacity is freed up. This feature improves the uptime of your VMs.

Skyline integration with vSphere health and vSAN health. 

Joining forces under the Skyline brand, Skyline Health for vSphere and vSAN are available in the vSphere Client, enabling a native, in-product experience with consistent proactive analytics.

Remove EZT for a shared disk. 

vSAN 7.0 eliminates the prerequisite that shared virtual disks using the multi-writer flag must also use the eager zero thick format.

Support vSAN memory as a metric in performance service. 

vSAN memory usage is now available within the vSphere Client and through the API.

Visibility of vSphere Replication objects in vSAN capacity view. 

vSphere replication objects are visible in vSAN capacity view. Objects are recognized as vSphere replica type, and space usage is accounted for under the Replication category.

Support for large capacity drives. 

Enhancements extend support for 32TB physical capacity drives and extend the logical capacity to 1PB when deduplication and compression are enabled.

Immediate repair after a new witness is deployed. 

When vSAN performs a replacement witness operation, it immediately invokes a repair object operation after the witness has been added.

vSphere with Kubernetes integration. 

CNS is the default storage platform for vSphere with Kubernetes. This integration enables various stateful containerized workloads to be deployed on vSphere with Kubernetes Supervisor and Guest clusters on vSAN, VMFS and NFS datastores.

File-based persistent volumes. 

Kubernetes developers can dynamically create shared (Read/Write/Many) persistent volumes for applications. Multiple pods can share data. vSAN native File Services is the foundation that enables this capability.

vVol support for modern applications. 

You can deploy modern Kubernetes applications to external storage arrays on vSphere using the CNS support added for vVols. vSphere now enables unified management for Persistent Volumes across vSAN, NFS, VMFS, and vVols.

vSAN VCG notification service.

You can subscribe to vSAN HCL components such as vSAN ReadyNode, I/O controller, drives (NVMe, SSD, HDD) and get notified through email about any changes. The changes include firmware, driver, driver type (async/inbox), and so on. You can track the changes over time with new vSAN releases.

Thursday, April 16, 2020

Logical design - storage performance sizing

Storage performance is always a kind of magic because multiple factors come in to play and not all disks are equal, however, in logical design, we have to do some math because capacity (and performance) planning is a very important part of logical design.

How I do it? I do math with some performance assumptions.

Here are assumptions about various disk type performance I use for my capacity planning exercises.

The below numbers are estimated for the random I/O of 64KB I/O size.

Mechanical hard drives
SAS 15k - 200 IOPS
SATA 7k - 80 IOPS

Read Intensive Solid-state disks (SSD)
SATA Read Intensive SSD - 5,000 IOPS (read) / 1,500 IOPS (write)
SAS Read Intensive SSD - 10,000 IOPS (read) / 2,000 IOPS (write)
NVMe Read Intensive SSD - 30,000 IOPS (read) / 2,500 IOPS (write)

Mixed Used Solid-state disks (SSD)
SATA Mixed Used SSD - 5,000 IOPS (read) / 1,800 IOPS (write)
SAS Mixed Used SSD - 12,500 IOPS (read) / 5,000 IOPS (write)
NVMe Mixed Used SSD - 45,000 IOPS (read) / 10,000 IOPS (write)

Write Intensive Solid-state disks (SSD)
SAS Write Intensive SSD - 12,500 IOPS / 7,500 IOPS (write)

SSD assumptions are based on hardware vendors' spec sheets. One of these spec sheets is available here

So with these assumptions, the performance math is relatively simple.

Let's have for example 4x SAS Read Intensive SSD within a disk group.
Such a disk group should have the aggregated read performance 4 x 10,000 IOPS = 40,000 IOPS

As we see in the performance numbers above, there is a significant performance difference between SSD read and write.

For our SAS Read Intensive SSD disk we have 10,000 IOPS for 100% read but only 2,000 IOPS for 100% write so we have to normalize these numbers based on expected read/write ratio. If the planned storage workload is 70% read and 30% write, we can assume the single SSD disk will give as 7,000 + 600 IOPS, so in total 7,600 IOPS.

Storage is typically protected by some RAID protection, where the write penalty comes into play. Write penalty is the number of I/O operations required on the backend for a single frontend I/O operation.

Here are write penalties for various RAID protections
RAID 0 (no protection) - write penalty 0
RAID 1 (mirror) - write penalty 2
RAID 5 (erasure coding / single parity) - write penalty 4
RAID 6 (erasure coding / souble parity) - write penalty 6

So, let's calculate the write penalty and write overhead.

If the planned storage workload is 70% read and 30% write and we have total aggregated normalized performance 30,400 IOPS (4 x 7,600) and we have to split the available performance into READ bucket and WRITE bucket.

In our example scenario, we have
READ bucket (70%) - 21,280 IOPS
WRITE bucket (30%) - 9,120 IOPS

Now we have to apply write penalty on write bucket. So let's say we would like to have RAID 5 protection, therefore 9,120 IOPS available on the backend can handle only 2,280 IOPS coming from the frontend.

Based on these calculations, the aggregated performance of RAID 5 protected disk group of 4 Read Intensive SSD disks should be able to handle 23,560 IOPS (21,280 + 2,280) of front-end storage workload.  Please note, that the considered workload pattern is random, 64KB I/O size with Read/Write ratio 70/30.

Do not forget, that this is just logical planning and estimation, every physical system can introduce additional overhead. In real systems, you can have bottlenecks not considered in this simplified calculation. Example of such bottleneck can be
  • storage controller, driver, firmware
  • low queue depth int the storage path (controller, switch, expander, disk), not allowing I/O parallelism
  • network or other bus latency
Therefore, any design should be always tested after implementation and performance results validated with expected numbers.

Are you doing similar design exercises? Any comment or suggestion is always welcome and appreciated.

Saturday, March 21, 2020

What's new in VMware vSphere 7

vSphere 7 has been announced and will be GA and available to download into our labs very soon. Let's briefly summarize what's new in vSphere 7 and put some links to other resources.

vSphere with Kubernetes

Project Pacific evolved into Integrated Kubernetes and Tanzu. vSphere has been transformed in order to support both VMs and containers. Tanzu Kubernetes Grid Service is how customers can run fully compliant and conformant Kubernetes with vSphere. However, when complete conformance with the open-source project isn’t required, the vSphere Pod Service can provide optimized performance and improved security through VM-like isolation. Both of these options are available through VMware Cloud Foundation 4.

The important takeaway is that Kubernetes is now built into vSphere which allows developers to continue using the same industry-standard tools and interfaces they’ve been using to create modern applications. vSphere Admins also benefit because they can help manage the Kubernetes infrastructure using the same tools and skills they have developed around vSphere.

Improved DRS

DRS used to focus on the cluster state and the algorithm would recommend a vMotion when it would benefit the balance of the cluster as a whole. This meant that DRS used to achieve cluster balance by using a cluster-wide standard deviation model. The new DRS logic computes a VM DRS score on the hosts and moves the VM to a host that provides the highest VM DRS score. This means DRS cares less about the ESXi host utilization and prioritizes the VM “happiness”. The VM DRS score is also calculated every minute and this results in a much more granular optimization of resources.

Another new feature is "DRS Scalable Shares". Scalable Shares solves a problem many have been facing over the last decade or so, which is that DRS does not take the number of VMs in the pool into account when it comes to allocating resources.

Refactored vMotions

Improvements in live migrations of monster workloads. Monster VMs with a large memory & CPU footprint, like SAP HANA and Oracle database backends, had challenges being live-migrated using vMotion. The performance impact during the vMotion process and the potentially long stun-time during the switchover phase meant that customers were not comfortable using vMotion for these large workloads. With vSphere 7, we are bringing back that capability as we have greatly improved the vMotion logic.

How the improvement was achieved?
  • Multi-threading
  • A dedicated vCPU is used for page tracing which means that the VM and its applications can keep working while the vMotion processes are occurring. Prior to vSphere 7, page tracing occurred on all vCPUs within a VM, which could cause the VM and its workload to be resource-constrained by the migration itself. 

Assignable Hardware

There is a new framework called Assignable Hardware that was developed to extend support for vSphere features when customers utilize hardware accelerators. It introduces vSphere DRS (for initial placement of a VM in a cluster) and vSphere High Availability (HA) support for VM’s equipped with a passthrough PCIe device or a NVIDIA vGPU. Related to Assignable Hardware is the new Dynamic DirectPath I/O which is a new way of configuring passthrough to expose PCIe devices directly to a VM. The hardware address of a PCIe device is no longer directly mapped to the configuration (vmx) file of a virtual machine. Instead, it is now exposed as a PCIe device capability to the VM.

Together, Dynamic DirectPath I/O, NVIDIA vGPU, and Assignable Hardware are a powerful new combination unlocking some great new functionality. For example, let’s look at a VM that requires an NVIDIA V100 GPU. Assignable Hardware will now interact with DRS when that VM is powered on (initial placement) to find an ESXi host that has such a device available, claim that device, and register the VM to that host. If there is a host failure and vSphere HA kicks in, Assignable Hardware also allows for that VM to be restarted on a suitable host with the required hardware available.


Bitfusion stays in vSphere 7 as a Tech Preview feature. It allows us to leverage hardware accelerators (GPUs) across an infrastructure (over network fabric) and integrate it with evolving technologies such as FPGAs and custom ASICs using the same infrastructure. This is actually the first implementation of the software-defined composable infrastructure within VMware SDDC stack, therefore it is a very promising and very needed technology for modern applications such as ML/AI workloads.

Precision Time Protocol (PTP)

Precision Time Protocol is helpful for financial and scientific applications requiring sub-millisecond accuracy. PTP requires VM Hardware 17 and it must be enabled on both an in-quest device and an ESXi service. Thus, you have to choose between NTP or PTP.

VM Template Management (Content Library)

VM template check-in and check-out operations with versioning feature. Content Library should also support of controlled replication into remote locations. With these vSphere 7 Content Library improvements, the Content Library is now a mature and very useful tool for VM template management.

vSphere Lifecycle Manager (vLCM)

Desired state of ESXi hosts image (divers & firmware) and host configuration assigned to vSphere Clusters. It requires integration with hardware vendor system management like Dell OMIVV (OpenManage Integration for VMware vCenter) or HPE OneView for VMware vCenter.

vSphere Update Planner

Update Planner is part of vLCM and it monitors current interoperability based on VMware HCL.

vCenter Server Profiles

Export / Import of VCSA (vCenter) configuration. This is good for effective management of a lot of vCenters but please, do NOT expect export/import of vCenter objects like Clusters, VM Folders, Resource Pools, Virtual Switches, etc... This is export / import of VCSA configurations.

VCSA multihoming

VCSA now supports multiple (up to 4) vNICs. The first vNIC (vNIC0) is for management, the second (vNIC1) is dedicated for vCenter Server HA and other vNICs can be used for other purposes like a backup or so.

vCenter and SSO Architecture

vCenter Server Appliance (VCSA) with embedded Platform Service Controler (PSC). External PSC is not supported and it leads into simple SSO topology.

Simplified Certificate Management

Much simpler SSL certificate management. Fewer certificates to manage. For example, vCenter has only two SSL certificates, a Machine SSL certificate, and Certification Authority Certificate. vSphere 7 introduced some vSphere Client UI improvements and also the REST API for certificate management for environments with more vCenters to manage. This is, of course, beneficial for environments implemented based on VMware Validated Designs (VVD) or VMware Cloud Foundation (VCF) environments which is the automated implementation of VVD.

Identity Federation

vCenter is not the key Identity Management System anymore. vSphere Client is using external authentication providers to optimize IDM integration in customer's environments. The first implementation supports only Microsoft Active Directory Federation Services (ADFS), however, VMware SSO still exists, therefore the customer can choose if he will use the brand new Identity Federation or keep existing AD/LDAP authentication through VMware SSO.

vSphere Trust Authority (vTA)

In vSphere 7, vCenter is not trusted authority anymore. vSphere 7 introduces vTA, which creates a hardware root of trust using a separate ESXi host cluster.

vSGX - Support of Intel Software Guard Extensions (SGX)

vSphere 7 introduces support of Intel Software Guard Extensions. I was blogging about SGX a few years ago in blog post Intel Software Guard Extensions (SGX) in VMware VM. Intel SGX allows applications to work with hardware to create a secure enclave that cannot be viewed by the guest OS or hypervisor. With SGX, applications can move sensitive logic and storage into this enclave. SGX is the Intel-only feature. AMD has SEV, which is a different approach.

vSphere 7 Configuration Maximums

Hosts per single vCenter: 2,500
Powered-on VMs on single vCenter: 30,000

Hosts per SSO domain (vCenters in linked mode): 15,000
Powered-on VMs per SSO domain (vCenters in linked mode): 150,000

vCenter Server Latency - vCenter <-> vCenter: 150 ms
vCenter Server Latency - vCenter <-> ESXi: 150 ms
vCenter Server Latency - vSphere Client (web browser) <-> vCenter: 100 ms

The improvements between vSphere 6.7 and 7 are clearly visible in figure below.

For further configuration maximums, look at

Skyline Health for vSphere 7

Skyline Health for vSphere 7 is the unified health check tool for vSphere which works exactly as Skyline Health for vSAN available since vSphere 6.7 U3. It brings into infrastructure operations similar approach developers are doing in agile development methods - automated testing. You can think about it as a set of tests (health check tests) continually testing everything works as expected.

NVMe over Fabric

In vSphere 7, VMware added support for shared NVMe storage using NVMeoF. For external connectivity, NVMe over Fibre Channel and NVMe over RDMA (RoCE v2) are supported.



vSphere 7 is another major vSphere Release. For those who work with VMware virtual infrastructures for ages (see old ESX 3i below), it is amazing where the VMware virtualization platform (vSphere 7, ESXi 7) evolved and what is possible nowadays.

Old good ESXi from Virtual Infrastructure 3 from 2006-ish year :-)
Nowadays, there are totally different reasons to upgrade to the latest vSphere version in comparison to the old days of server consolidation, TCO reduction, and better manageability. Top reasons to upgrade to vSphere 7 are
  • Scalability: The fastest path to the Hybrid/Multi-Cloud and increase scalability through leveraging HCI (Hyper-Converged Infrastructure) 
  • Security: Infrastructure security, secure audits, and account management
  • Performance: maximize performance and efficiency
  • Manageability: Reduce complexity, simplify software patching and hardware upgrades, proactive support technology and services
VMware vSphere 7 new features and incorporation of containers (Kubernetes) into the single platform is another step into VMware's vision to run any app on any cloud. On vSphere 7, you can run
  • monster workloads such as SAP HANA
  • traditional applications in virtual machines
  • modern distributed applications (Cloud Native Applications, CNA) containerized and orchestrated by Kubernetes
This is a great message to all of us, who invested a lot of time (years) to learn, test, design, implement and operate VMware technologies. I can honestly say, ... I LOVE VMWARE ...

Thursday, March 19, 2020

Home Lab 2019/2020

First thing first. Why I have the home lab(s)?

Well, I really need at least one home lab to test and demonstrate VMware vSphere, vSAN, NSX and other components of VMware SDDC stack.

The other reason is, that from time to time I have discussions with other VMware folks discussing our home lab configurations and some of these people have the blog post about their labs. I have never written the blog post about my home lab so far but I realized it is quite useful to document at least some basic information about the lab to quickly show lab details during these discussions and demonstrations. So, here it is.

At the moment, I have two home labs
  1. One in a garage - GARAGE LAB
  2. Second in a flat - APARTMENT LAB
Here are the photos and quick descriptions of my home labs. 


GARAGE LAB vSphere/vSAN Cluster specification
  • 4-node vSphere Cluster (4x ESXi on Dell PE R620) with hybrid vSAN Enabled (4x NVMe 512 GB as cache disks, 8x SATA 500 GB as capacity disks)
  • Each node has 1 CPU Socket (Intel Xeon CPU E5-2620 @ 2.00GHz), 128 Gb RAM, 4x 1Gb Ethernet Port, 1x NVMe 512 GB, 2x SATA 500 GB
GARAGE LAB external storage
  • Flash NAS (NFS) Storage - Synology DS115j , 1x SSD 840 Series 512 GB (465.76 GB SSD)
  • Flash iSCSI Storage - Synology DS115j , 1x SanDisk Ultra II 960 GB (894.3 GB SSD)
  • SATA NAS (NFS) Storage - Synology DS214se, 2x SATA Disk 3TB (2794.52 GB HDD) 

APARTMENT LAB vSphere/vSAN Cluster specification
  • 4-node vSphere Cluster (4x ESXi on Intel NUC) with All-Flash vSAN Enabled (4x SATA M.2 SSD 180 GB as cache disks, 4x SATA SSD 480 GB as capacity disks)
  • Each node is Intel NUC (6i3SYH) having 1 CPU Socket (Intel Core i3-6100U CPU @ 2.30GHz), 32 GB RAM, 1x 1Gb Ethernet Port, 1x SATA M.2 SSD 180 GB, 1x SATA SSD 480 GB
VMware Licensing

As I'm VMware Certified Design Expert, I'm automatically (after application) awarded as VMware vExpert thus entitled to use VMware vSphere Licenses for almost all VMware products. This is IMHO one of the biggest advantages to be VCDX and/or participate in the VMware vExpert program.

Tuesday, February 11, 2020

Host cannot communicate with one or more other nodes in the vSAN enabled cluster

I work as VMware HCI Specialist, therefore I have to do a lot of vSAN testing and demonstrations in my home lab. The only reasonable way how to effectively test and demonstrate different vSAN configurations and topologies is to run vSAN in a nested environment. Thanks to a nested virtualization, I can very easily and quickly build any type of vSAN cluster.

Recently I have experienced the issue in 3-node (nested) vSAN cluster. I have seen vSAN datastore capacity just of a single node instead of three nodes and on hosts was an error message "Host cannot communicate with one or more other nodes in the vSAN enabled cluster".

The first idea was about networking issue but ping between nodes was working ok so it was not a physical network issue. This is the lab environment so all services (mgmt, vMotion, vSAN) are enabled on single VMKNIC (vmknic0) so everything is pretty straight forward.

So what's the problem?

I did some google searching and found that some people were seeing the same error message when experiencing problems with vSAN unicast agents.

Here is the command to list of unicast agents on vSAN node

esxcli vsan cluster unicastagent list

I test it in my environment.
Grrrr. The list is empty!!!! It is empty on all ESXi hosts in my 3 nodes vSAN cluster.

Let's try to configure it manually.

Each vSAN node should have a connection to agents on other vSAN nodes in the cluster.

For example, one vSAN node from 4-node vSAN Cluster should have 3 connections

 [root@n-esx04:~] esxcli vsan cluster unicastagent list  
 NodeUuid               IsWitness Supports Unicast IP Address    Port Iface Name Cert Thumbprint  
 ------------------------------------ --------- ---------------- -------------- ----- ---------- -----------------------------------------------------------  
 5e3ec640-c033-7c7d-888f-00505692f54d     0       true 12321       18:F3:B7:9F:66:C4:C4:3E:0F:7D:69:BB:55:92:BC:A3:AC:E4:DD:5F  
 5df792b0-f49f-6d76-45af-005056a89963     0       true 12321       20:4C:C1:48:F5:2D:04:16:55:F1:D3:F1:4C:26:B5:C4:23:E5:B4:12  
 5e3e467a-1c1b-f803-3d0f-00505692ddc7     0       true 12321       53:99:00:B8:9D:1A:97:42:C0:10:C0:AF:8C:AD:91:59:22:8E:C9:79  

We need the get local UUID of the cluster node.

 [root@n-esx08:~] esxcli vsan cluster get  
 Cluster Information  
   Enabled: true  
   Current Local Time: 2020-02-11T08:32:55Z  
   Local Node UUID: 5df792b0-f49f-6d76-45af-005056a89963  
   Local Node Type: NORMAL  
   Local Node State: MASTER  
   Local Node Health State: HEALTHY  
   Sub-Cluster Master UUID: 5df792b0-f49f-6d76-45af-005056a89963  
   Sub-Cluster Backup UUID:  
   Sub-Cluster UUID: 52c99c6b-6b7a-3e67-4430-4c0aeb96f3f4  
   Sub-Cluster Membership Entry Revision: 0  
   Sub-Cluster Member Count: 1  
   Sub-Cluster Member UUIDs: 5df792b0-f49f-6d76-45af-005056a89963  
   Sub-Cluster Member HostNames:  
   Sub-Cluster Membership UUID: f8d4415e-aca5-a597-636d-005056997c1d  
   Unicast Mode Enabled: true  
   Maintenance Mode State: ON  
   Config Generation: 7ef88f9d-a402-48e3-8d3f-2c33f951fce1 6 2020-02-10T21:58:16.349  

So here are my nodes
n-esx08 - - 5df792b0-f49f-6d76-45af-005056a89963
n-esx09 - - 5df792b0-f49f-6d76-45af-005056a89963
n-esx10 - - 5df792b0-f49f-6d76-45af-005056a89963

And now the problem is clear. All vSAN nodes have the same UUID.
Why?  Let's check ESXi system UUIDs on each ESXi host.

 [root@n-esx08:~] esxcli system uuid get  

 [root@n-esx09:~] esxcli system uuid get  

 [root@n-esx10:~] esxcli system uuid get  

Note: if you want to check UUID of all ESXi hosts, use following PowerCLI

 Get-VMHost | Select Name,  
   @{N='HW BIOS Uuid';E={$_.Extensiondata.Hardware.SystemInfo.Uuid}},  
   @{N='ESXi System UUid';E={(Get-Esxcli -VMHost $_).system.uuid.get()}}  

So the root cause is obvious.
I use nested ESXi hosts to test vSAN and I forgot to regenerate system UUID after the clone. 
The solution is easy. Just delete UUID from /etc/vmware/esx.conf and restart ESXi hosts.

ESXi system UUID in /etc/vmware/esx.conf

You can do it from command line as well

sed -i 's/system\/uuid.*//' /etc/vmware/esx.conf

So we have identified the problem and we are done. After ESXi hosts restart vSAN Cluster Nodes UUIDs are changed automatically and vSAN unicastagents are automatically configured on vSAN nodes as well.

However, if you are interested in how to manually add a connection to a unicast agent on a particular node, you would execute the following command

esxcli vsan cluster unicastagent add –a [ip address unicast agent] –U [supports unicast] –u [Local UUID] -t [type]

Anyway, such a manual configuration should not be necessary and you should do it only when instructed by VMware support.

Hope this helps someone else in VMware community.

Saturday, February 01, 2020

vSphere Integrated Containers - PoC in my home lab

vSphere Integrated Containers (aka VIC) is VMware Enterprise Container Infrastructure. Any VMware customer having VMware vSphere Enterprise Plus can get enterprise container infrastructure to help IT Ops run traditional and containerized applications side-by-side on a common platform with vSphere Integrated Containers. Supporting containers in your virtualized environments means IT teams get the security, isolation, and management of VMs, while developers enjoy the speed and agility of containers—all within vSphere. The VIC project is available on GitHub at

The overall concept is very interesting, especially for customers willing to use Docker containers but not having requirements or skills to operate Kubernetes. The most interesting part of VIC is the networking concept very well explained in following video

As one of my customers is considering VIC to provide containers to their developers, I have decided to test it in my home lab.

The first step is to deploy VIC from OVF. It's pretty straight forward so I'm not going to document any details.

The second step is to create the first VCH (Virtual Container Host), which acts as a remote Docker server. You can have multiple VCH's and they can be grouped into projects. Let's keep architectural decisions besides at the moment and focus on testing the technology itself.

VCH deployment is typically done via vic-machine CLI Utility as GUI is too slow interface for DevOps approach. Documentation is available at

VIC-MACHINE ... is the primary tool for DevOps admin. I will discuss roles, tooling, and RBAC for particular actors in DevOps approach in the next blog post together with the overall architecture.

We can download vic-machine from VIC appliance deployed in step 1. In my case, it is available at

When we have vic-machine available in our DevOps workstation we can start act as a DevOps engineer.

Note 1: 
If you have self-signed certificate as I have in my lab, you need to get vCenter Thumbprint.You have to ssh to vCenter Server Appliance and get the fingerprint.
openssl x509 -in /etc/vmware-vpx/ssl/rui.crt -fingerprint -sha1 -noout
The vCenter thumbprint in my lab is
SHA1 Fingerprint=64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9
Note 2: 
vic-machine tool is available for various operating systems (windows, linux, darwin).  As my workstation is Mac OS X (aka darwin), in commands below I will use ./vic-machine-darwin

Before the first VCH deployment, we have to enable the firewall rules in a particular vSphere cluster (the name of vSphere Cluster in my home lab is CLUSTER).

./vic-machine-darwin update firewall --target --thumbprint 64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9 --user --compute-resource CLUSTER --allow

Now we are ready to create our first VCH.

Here is the command, how to create VCH.

./vic-machine-darwin create --name vch01 --container-name-convention vch01-{name} --compute-resource CLUSTER --image-store vsan-Underlay --base-image-size 8GB --bridge-network VCH01-BRIDGE --bridge-network-range --public-network MGMT --dns-server --container-network CONTAINER01:container01 --container-network-ip-range CONTAINER01: --container-network-gateway CONTAINER01: --container-network-dns CONTAINER01: --container-network-firewall CONTAINER01:published --tls-cname vch01 --certificate-key-size 2048 --no-tlsverify --user admin@UW.CZ --thumbprint 64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9 --target --ops-user administrator

The output from the command looks similar to ...

INFO[0068] VCH Admin Portal:                            
INFO[0068] VCH Default Bridge Network Range: 
INFO[0068] VCH Default Bridge Network Width: 16         
INFO[0068] Published ports can be reached at:           
INFO[0068] Management traffic will use:                 
INFO[0068] Docker environment variables:                
INFO[0068] Environment saved in vch2/vch2.env           
INFO[0068] Connect to docker:                           
INFO[0068] docker -H --tls info      
INFO[0068] Installer completed successfully             

Davids-MacBook-Pro:vic-machine dpasek$ 

My first VCH has been created with a single container network (network name CONTAINER01). To add another container network (CONTAINER02) we need to know VCH id, therefore inspect command has to be used.

./vic-machine-darwin inspect --target --thumbprint 64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9 --user --compute-resource CLUSTER --name vch2

INFO[0005] VCH ID: vm-299                               
INFO[0005] VCH Admin Portal:                            
INFO[0005] VCH Default Bridge Network Range: 
INFO[0005] VCH Default Bridge Network Width: 16         
INFO[0005] Published ports can be reached at:           
INFO[0005] Management traffic will use:                 
INFO[0005] Docker environment variables:                
INFO[0005] Connect to docker:                           
INFO[0005] docker -H --tls info      

INFO[0005] Completed successfully  

Note that to configure additional network we have to add all already existing networks into the command as well.

./vic-machine-darwin configure --target --thumbprint 64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9 --user --id vm-299 --container-network CONTAINER01 --container-network CONTAINER02

Docker client is using VCH (aka Virtual Container Host) as a docker server

docker --tls info
docker --tls network ls

Here is the output of the networks available in my Docker host (aka Virtual Container Host)

dpasek@photon-machine [ ~ ]$ docker --tls network ls   
NETWORK ID          NAME                DRIVER              SCOPE
4313b6b0ab2e        CONTAINER01         external            
6eb9e8911266        bridge              bridge              

dpasek@photon-machine [ ~ ]$ 

and after vic-machine command to add additional network CONTAINER02 you can see the network in container host (VCH) and use it for our containers.

dpasek@photon-machine [ ~ ]$ docker --tls network ls
NETWORK ID          NAME                DRIVER              SCOPE
4a8318cb2738        CONTAINER01         external            
a011cf3ced72        CONTAINER02         external            
7445a9e714ed        bridge              bridge              

dpasek@photon-machine [ ~ ]$ 

Of course, we can use other standard docker commands to manage our docker images and containers.

docker --tls images -a
docker --tls ps -a

Run NGINX and access the service through NAT
docker --tls run --name nginx1 -d –p 8080:80 nginx
docker --tls ps -a
docker --tls images -a

Run NGINX and access the service directly through container network (IP address assigned via DHCP) 
docker --tls run --name nginx2 --network="container01" -d -p 80 nginx

Run NGINX and access the service directly through container network (IP address assigned staticaly) 
docker --tls run --name nginx30 --network="container01" --ip="" -d -p 80 nginx

Execute a Shell Command from a Container
docker --tls run busybox date
docker --tls ps -a

In the screenshot below you see what vSphere Admin has in his environment.

Containers visibility for vSphere Admin

Specific container (nginx) visibility for vSphere Admin
Docker Volumes

If you need persistent storage for your containers, you can create volumes which are persistently stored in your enterprise infrastructure and visible not only to DevOps admin and Developer, but also to your infrastructure administrator.

Create a Docker Volume
docker --tls volume create --opt Capacity=2GB --name volume-test
docker --tls volume ls
docker --tls volume inspect volume-test

Attach a Docker Volume to a Container
docker --tls run --name busybox -it -v volume-test:/data/volume-test busybox
# cd /data
/data # ls
/data # ls –l
total 4
/data # df -h
This is what Developer and DevOps admin see via Docker Client

dpasek@photon-machine [ ~ ]$ docker --tls volume ls

vsphere             volume-test

And this is what vSphere Admin can see in his environment

Docker volume (2 GB) is visible as 1.92 GB Hard Disk
List VCH instances

DevOps admin manages Virtual Container Hosts. Here is the command to list all VCH's from a particular vCenter.

./vic-machine-darwin ls --target --thumbprint 64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9 --user

Davids-MacBook-Pro: vic-machine dpasek$ ./vic-machine-darwin ls --target --thumbprint 64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9 --user 
INFO[0000] vSphere password for    
INFO[0003] ### Listing VCHs ####                        
INFO[0003] Validating target                            

ID            PATH                                         NAME        VERSION                      UPGRADE STATUS
vm-299        /SDDC/host/UNDERLAY/CLUSTER/Resources        vch2        v1.5.4-21221-b3d3b06f        Up to date

Davids-MacBook-Pro:vic-machine dpasek$ 

Delete VCH

And here is the command to destroy particular VCH.

./vic-machine-darwin delete --target --thumbprint 64:06:CD:4E:D8:39:8B:E8:80:2D:D3:25:50:C7:B9:7D:E1:6F:8B:E9 --user --name vch2 --compute-resource CLUSTER


DevOps is a big topic nowadays. It is worth to say that DevOps is about methodology and not the tooling. At the end of the day, it doesn't matter if you use Docker, Kubernetes, Ansible or even more traditional tools. What matters is the final product which has to be developed in sync with the business owner, otherwise, there is a high chance you are not meeting business owner expectations. I'm ex-developer, Software Engineer / Architect and now I work as an Infrastructure Technical Designer / Architect, therefore I know, the DevOps methodology is the best way how to develop and deliver a business application to the business owner. The key principles of DevOps methodology are to identify the core business requirements, quickly develop the application prototype, present it to the business owner, validate if the business owner expectations are met and if so, move the prototype into production and continuously develop and deploy additional business requirements in short iterations with continuous feedback from the business owner. For such an approach, you need to deploy your application into infrastructure dynamically and quickly. Traditional Enterprise Infrastructure is not ready for such agility.

In this blog post, we were testing the tool (VMware vSphere Integrated Containers) which can help Developers, DevOps admins and infrastructure admins cooperate in an agile fashion. It might or might not help to deliver successfully the business project. However, it definitely helps DevOps teams to have agile DevOps infrastructure with Enterprise level of support, security, availability, and cooperation between Developers, Security, and Infrastructure (compute, storage, network) teams which each lives in the totally different world and they do not understand each other :-)

In my opinion, vSphere Integrated Containers is a great technology to start DevOps in the Enterprise environment. We all know that Enterprises will eventually adopt Kubernetes as it is nowadays a "de facto" standard for DevOps infrastructure, however huge Docker Hosts backed by solid enterprise infrastructure (VMware vSphere) is good enough for anybody just starting with DevOps methodology. In the near future, VMware vSphere will have integrated Kubernetes (watch the Project Pacific) and DevOps teams will be able to transform their DevOps tooling into another level.

In the next post, I will focus on the Architecture Design of DevOps environment leveraging VMware vSphere Integrated Containers.

Hope this blog post helps at least one other person in the great VMware community.

Friday, January 31, 2020

VMware vSphere Replication

VMware vSphere Replication is a software-based replication solution for virtual machines running on vSphere infrastructure. It is storage agnostic so it can replicate VMs from any source storage to any target storage. Such flexibility and simplicity is the biggest value of vSphere Replication. It doesn't matter if you have Fibre Channel, DAS, NAS, iSCSI or vSAN based datastores you can simply start full replica from any to any datastore and based on defined RPO your data are in sync between two places.

It is very simple to install and use solution and also very cost-effective as it is included in all vSphere Editions higher than vSphere Essential Plus.

The installation is straight forward

  1. Download the installation package (ISO)
  2. Mount ISO
  3. Deploy OVF (Virtual Appliance in Open Virtual Format)
  4. Configure Virtual Appliance to register into vCenter

The installation package is in the OVF format. You can deploy the package by using the Deploy OVF wizard in the vSphere Client. 

The installation package contains
  • vSphere_Replication_OVF10.ovf - Use this file to install all VR components, including the vSphere Replication Management Server and a vSphere Replication Server.
  • vSphere_Replication_AddOn_OVF10.ovf - Use this file to install an optional additional vSphere Replication Server.
Of course, there are some solution limitations. Let's write down some of them
  1. vSphere Replication supports RPO 5 min and higher, therefore it is an asynchronous replication and you cannot use it if you have strict RPO Zero requirement. However, do your business really require RPO Zero? Do not hesitate to ask and challenge somebody responsible for Business Impact Analysis and costs associated with it. Do not simply assume you cannot lose any data. There should always be a risk management exercise.
  2. vSphere Replication is a one-to-one VM mapping and not one-to-many. While you can replicate to multiple vCenters (target sites), only one VM can be replicated to one target vCenter. Here are further details and supported topologies
  3. vSphere Replication supports up to 24 recover points. These 24 recover points can have retention for up to 24 days or you can configure up to 24 snapshots per 1 day. So you can spread these 24 recover points within these guide rails based on your specific business requirements.
As vSAN does not have any native storage replication, vSphere Replication is the great add on to VMware HCI solution. If you have higher requirements you can leverage 3rd party solutions like EMC Recoverpoint, which is by the way included in the VxRAIL hardware appliance.

For more information see the vSphere Replication online documentation at