Saturday, November 23, 2013

Site Recovery Manager and vSphere Replication Network Ports Required - Simplified!

Sunny Dua published very usefull blog post describing SRM network ports among different SRM software components. When you need to known what ports are required for SRM look at

Thursday, November 21, 2013

Qlogic HBA adapter Queue depth in windows 2008 r2

Here is interesting discussion about the topic ... bellow are the most valuable statements from the thread:

By default a QLogic HBA Execution Throttleis set to 16.  This setting specifies the maximum number of outstanding (SCSI / Fiber Channel) commands that can execute on any single Target port(WWPN).  When a Target port’sExecution Throttleis reached, the host computer will not issue any new commands until one of the current commands finishes executing.

To increase the number of outstanding (SCSI / Fiber Channel) commands to the Target port,increase the Execution Throttle.  However, increasing the Execution Throttlebeyond what the Target portmay handle will cause SCSI timeouts to occur.

According to QLogic it is considered a Best Practiceto optimize performance for all devices that may communicate with the Target port. To do this QLogic recommends that you divide the Target port'sMaximum Outstanding Commands (or Queue) by the number of host ports (Initiators) that access the Target port.  This type of computation is used to determine the Target portfan-in ratio as well.

(Maximum Storage Port Command Queue) / (Host Ports) = Execution Throttle


Ideally Storage team has to tell what is the QD that needs to be set on the HBA based on how many LUNS are published on a particular port

Queue depth is the number of I/O operations that can run in parallel on a device

Calculating the queue depth\Execution Throttle value

To prevent flooding the target port queue depth, the result of the combination of number of host paths + execution throttle value + number of presented LUNs through the host port must be less than the target port queue depth. In short T => P * q * L

T = Target Port Queue Depth
P = Paths connected to the target port
Q = Queue depth
L = number of LUN presented to the host through this port


Wednesday, November 13, 2013

VMware ESXi vim-cmd Command: A Quick Tutorial

Very nice blog post on ...
Command lines are very important for system administrors when it comes to automation. Although GUIs are more likely (not always as I’ve seen too many bad ones) to be more intuitive and easier to get started with, sooner or later administrators will use command lines more for better productivity. There are a few command line options in VMware ESXi, among which is the vim-cmd ... READ MORE.

Tuesday, November 12, 2013

Introduction to the Dell S6000 Layer 2 Gateway for VMware NSX

On following video you can see DELL Force10 S6000 integration with VMware NSX. That's beginning of real and usable software defined networking (SDN) or network virtualization if you wish.

 I'm looking forward for hands-on experience in the future.