Seeking Storage Reclamation Guidance

[proden20]

I have been tasked with estimating the total reclaimable space consumed by vSphere across 2 of our arrays.  We are upgrading to vSphere 5.0  in the coming week or two, and I'd love to get some feedback on how you are all handling/estimating the following across your datacenters:

- Calculating total reclaimable space now consumed by snapshots

- Calculating reclaimable free space within the guest OS

- Calculating reclaimable space by moving to thin provisioning with vmkfstools whitespace reclamation

- Any space management benefits of VMFS 5

- Any other tips or tricks for reclaiming space, particularly anything involving IBM XIV or V7000 arrays

I used to use some pretty handy PowerCLI scripts provided by Quest, but I don't think these tools are available for vSphere 5.x.

Thanks!!!!

[Alim786]

I don't personally know of any specific scripts to get what you want but the link below gives a list of various tools which may get you what you want with a little customizing. I have used some of the tools before to get what I need. I am sure you will find this useful :-

http://www.kendrickcoleman.com/index.php/Tech-Blog/vm-advanced-iso-free-tools-for-advanced-tasks.htm...

Good Luck !

[Gkeerthy]

Spce reclaimation is realy a tough topic ..

Depending upon the array the space reclaimation varies, because the when you create a LUN as thin, many things you need to consider.

1- you need to check if you have enterprise license, then only you get the VAAI features

2- you array is VAAI capable

With the latest vsphere5.0 update2 and 5.1, the esxi UNMAP issue is solved

So basically the reclimation happens or need to do in 3 level

1- In the Operation system level, that is using SDELETE for windows, FSTRIM for linux, but for EXT4 linux os it is inbuilt, and you can do it maually or automatically. For windows 2012 also it will happend automatically

http://en.community.dell.com/techcenter/b/techcenter/archive/2011/06/29/native-free-space-recovery-i...

2-In the VMFS level, you can use the vmkfstools in the latest esxi, to recaim

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=201484...

3- In the storage level, in the storage array also some times you need to do. Some arrays it dont need,

- Calculating total reclaimable space now consumed by snapshots - you will get this in the storage views from the vcenter

- Calculating reclaimable free space within the guest OS and Calculating reclaimable space by moving to thin provisioning with vmkfstools whitespace reclamation - i dont think any formula exists, 100 % answer is difficult

- Any space management benefits of VMFS 5 - it has, now vmfs supports the UNMAP, that is good. More over, it has other great features like 64 tb single LUN, full support for VAAI, 1 mb block size,

also check the VMFS heap size, this is important thing we need to check. refer my blog - http://pibytes.wordpress.com/2012/11/13/esxi-vmfs-heap-size-blockade-for-monster-virtual-machines-in...

[griffinboy]

To add my 2 pence to Gkeerthy's comments, if your storage supports VAAI and UNMAP, there is a great article from Cormac Hogan showing it in action here: http://blogs.vmware.com/vsphere/2012/04/vaai-thin-provisioning-block-reclaimunmap-in-action.html

This should at least put you on the right track I hope.

Thanks for sharing your results if you get somewhere, as I will probably be looking into this too at some point soon

[proden20]

Excellent feedback fine people!  I shall absorb it, apply it, and share my experiences.  I have a feeling the array-level work will be challenging.  IBM's XIV firmware has been pretty flaky on our Gen2.  It's a great array but sure exhibits some unpredictable behavior.

[proden20]

Thinking on your feedback....

- Yep, this is gonna be tough 🙂

- Our XIV has VAAI but I won't know if the UNMAP primitive is available (or work) until IBM puts new code on it in a few weeks.  Haven't had much luck with their VAAI code in the past (4.x)

- Can I avoid the UNMAP issue altogether by evacuating the VM's on VMFS3 LUNs with svMotion-to-thin-disk on 1MB VMFS5?  Subsequently I could destroy the VMFS3 volumes on the XIV and let it perform reclaim on its own?

- I looked at SDELETE.  The description seemed to indicate that it overwrites with its own pattern.  How does SDELETE reclaim space?

- I checked out your article on adjusting heap size.  We'll definitely keep that in mind!

Thanks!

Dennis

[pjo65]

Hi Proden 20!

i know i'm a litte late but...

Have had the same problem as you and i have done this:

From the v7000 create a new thin or compressed mirrored copy of the volume in question.

When the copy i finished you make the new copy primary, and then delete the original.

In this way you don't have to bare load to your ESX's.

The downside to this is:

a: It can't be automated

b: You must have enough free space available in v7000.

I know this solution only solves the v7000 side but there is an easy way i VMWare.

Create a volume of different block size then the your other volumes.

Do a storage vmotion to that storage.

This assumes that the guest has thin vdisks or that you specify thin as target.

Good luck.