vsphere 4.1 and P2000 G3 storage - loss of space on presenting to vmware

[Jules82]

Hello, I wonder if anyone has any experience with p2000 storage and vsphere 4.1.

We currently run an environment with 4 vsphere hosts (4.1), vcentre, mixed NetApp (FAS2050A) and HP storage. When presenting volumes from the NetApp we would expect to lose a small percentage of this volume around 1% (if that) for the datastore seen in vmware, however upon recently presenting volumes from the p2000 G3 iSCSI storage we're losing more like 10% which is considerably more. This also happens it would seem if we connect the volume through iscsi on a vm itself running windows, so I am leaning towards this being more of a storage level setting than a reason in vmware as to why this may be happening, however I just wondered if anyone has any experience with this happening for them?

:smileyconfused:

Thanks

[marcelo_soares]

What is the size of the LUN you are presenting and with what size the ESX detects it?

[MauroBonder]

Hello,

Please read all limitation of block size here -->http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=100356...

If your lun its ok base on this kb, try restart management via ssh to refresh all information about Storage .

Good luck

[Jules82]

Hi marcelo.soares,

The size of the luns vary so one for example is: 170GB ESX see's this as 158GB

                                                     another is: 400GB ESX see's this as 372.50GB

Thanks J

[Jules82]

Also, the HP stroage has a max block size of 64k where as I set the block size on vmware as 1MB when attaching, would this be affecting it at all? I'll maybe have a play with the block sizing between the two and see if this makes any difference to the loss of datastore space. I know that the max block size on the HP is definitely smaller to what the NetApp provides.

[jim33boy]

Hi Jules,

Whatyou see is normal.

The P2000 presents in base 10 by default.. 1GB = 10 to the 3rd power = 1000.  While ESXi or computers in general sees in base 2.. so 2 to the 10th power = 1024.

So your numbers are exactly correct.

400 * (1024^3) = 400000000000 -- 400 hundred billion base 10 bytes = 400 base 10 GB

400000000000 / (1024^3) = 372.5 -- 372.5 actual base 2 gigabytes.

You can set the users on the P2000 to display in base 2 or base 10.

Jimmy