Thursday, May 19, 2016

ESXi 6 - manual partitioning for multiple VMFS filesystems on single disk device

I have to test SDRS initial placement exact behavior (blog post here) therefore I need multiple VMFS datastores to form an Datastore Cluster with SDRS. Unfortunately, I'm constraint with storage resources in my home lab therefore I would like to use one local 220GB SSD to simulate multiple VMFS datastores.

Warning: This is not recommended practice for productional systems. It is recommended to have single partition (LUN) per single device.

I did not find GUI way how to create multiple partitions per single disks therefore I used CLI.

You cannot use old good fdisk for VMFS partitions. Instead PartedUtil has to be used because of GPT. PartedUtil is included in ESXi so you can login to ESXi over SSH and use partedUtil.

Note: It is worth to mention that you can have maximally 16 partitions in GUID Partition Table (GPT) in ESXi 6. This is what I have tested. When I tried to create 17 partitions the partedUtil failed with message - "Too many partitions (17)". 

In my lab I have Intel NUC with local SSD identified as "t10.ATA_____INTEL_SSDMCEAW240A4_____________________CVDA4426003E240M____".

To get partition table use following command

 partedUtil getptbl "t10.ATA_____INTEL_SSDMCEAW240A4_____________________CVDA4426003E240M____"  

If disk is empty you should see follwoing output:
29185 255 63 468862128
I would like to have 5 x 10Gb LUNs.

10Gb is 20971519 in sectors. Sector is 512Bytes

First 2048 should be skipped to keep space for GPT and to be aligned with 512B sectors. Below is my partition plan in format [Partition number, Start sector, End Sector]
P1 2048-20973567
P2 20973568-41945087
P3 41945088-62916607
P4 62916608-83888127
P5 83888128-104859647
Following command is used to create these 5 partitions.

 partedUtil setptbl "t10.ATA_____INTEL_SSDMCEAW240A4_____________________CVDA4426003E240M____" gpt "1 2048 20973567 AA31E02A400F11DB9590000C2911D1B8 0" "2 20973568 41945087 AA31E02A400F11DB9590000C2911D1B8 0" "3 41945088 62916607 AA31E02A400F11DB9590000C2911D1B8 0" "4 62916608 83888127 AA31E02A400F11DB9590000C2911D1B8 0" "5 83888128 104859647 AA31E02A400F11DB9590000C2911D1B8 0"  

Now you can list partitions again and you should see following output:
29185 255 63 468862128
1 2048 20973567 AA31E02A400F11DB9590000C2911D1B8 vmfs 0
2 20973568 41945087 AA31E02A400F11DB9590000C2911D1B8 vmfs 0
3 41945088 62916607 AA31E02A400F11DB9590000C2911D1B8 vmfs 0
4 62916608 83888127 AA31E02A400F11DB9590000C2911D1B8 vmfs 0
5 83888128 104859647 AA31E02A400F11DB9590000C2911D1B8 vmfs 0 

So we have 5 partitions and the last step is to format it to VMFS5 file system. We have to leverage vmkfstools which is also included in ESXi 6 system.

Let's start with first partition and we will use datastore name Datastore1.

 vmkfstools -C vmfs5 -S Datastore1 t10.ATA_____INTEL_SSDMCEAW240A4_____________________CVDA4426003E240M____:1  

The same procedure has to be repeated for each partition.

Here is Perl script which generates commands for partedUtil and vmkfstools based on several variables.
 my $disk_device = "t10.ATA_____INTEL_SSDMCEAW240A4_____________________CVDA4426003E240M____";  
 my $starting_sector = 2048;  
 my $partition_size_in_sectors = 4000000;  
 my $datastore_prefix = "Datastore";  
 my $num_of_partitions = 16; # Maximum is 16 partitions  
 my $partitions;  
 my $start = $starting_sector;  
 my $end;  
 my $i;  
 # Generate command for GPT partitions  
 for ($i=1; $i<$num_of_partitions; $i=$i+1) {  
     $end = $start + $partition_size_in_sectors;  
     $partitions .= "\"$i $start $end AA31E02A400F11DB9590000C2911D1B8 0\" ";  
     $start = $end + 1;  
 print "partedUtil setptbl \"$disk_device\" gpt $partitions\n";  
 # Generate commands to format partitions with VMFS5 file system  
 for ($i=1; $i<$num_of_partitions; $i=$i+1) {  
     print "vmkfstools -C vmfs5 -S $datastore_prefix$i $disk_device:$i\n";  

If you want to unmount 16 datastores it is very handy to use following command line:

 esxcli storage filesystem unmount -l Datastore1   

Hope this helps at least one other vSphere dude in his lab exercises. 

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