How big can a vmdk be in relation to the size of the datastore?

[khenry567]

Hey guys,

I am looking for some information on how to size my vmdk disk in relation to the size of the datastore. In particular, I have a datastore with 267.25gb of capacity with 266.70gb of free space. It is RAID 10. It will be used for an Exchange 2007 database only and is not RDM. It is formatted in 2mb block. I want to create the largest disk vmdk in this datastore that I can. How big can that be while still allowing for any of the other files that get put on that same datastore in the normal course of operations such as Ranger backup, short term snapshot creation, etc.?

I am looking but haven't found any info dealing in particular with this though I am sure it is there.

Thanks for your help. Kieth

[schepp]

Hi,

here's a list of max vmdk filesize per block size:

Blocksize - max Filesize

1MB - 256GB

2MB - 512GB

4MB - 1024GB

8MB - 2048GB

So you can use your whole datastore.

[continuum]

the problem with ranger backups is that they often leave orphaned snapshots on the volume

the problem with short-term snapshots is that often short-term snapshots will be forgotten

if you monitor the free space often you can create a larger vmdk - if you are lazy use a smaller one

I do not think that there is a safe value - it depends on your snapshot usage




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VMX-parameters- Workstation FAQ -[ MOA-liveCD|http://sanbarrow.com/moa241.html] - VM-Sickbay

[khenry567]

Hey schepp,

Thanks for the reply. I was aware of the block size/file size relationship. What I am looking for is to create one vmdk which will be the only vmdk on this datastore. If it is the only vmdk/file how big can it be in % of total datastore size and still give leeway for snapshots and/or other files that are created on that datastore along with the vmdk? Is there a rule-of-thumb? Is there a whitepaper on this?

[khenry567]

Hey continuum,

Thanks for the reply. Can you read my reply to schepp and respond to that also. Thanks

[continuum]

it all depends on your discipline with snapshots -if you monitor them well and make sure short term snapshots really are short term snapshots I would use up to 3/4 of the volume but not more.

Make sure you keep an eye on the ranger snapshots.

In case you run out of space during a snapshot operation there is not much hope for recovery - so better be safe than sorry




___________________________________

VMX-parameters- Workstation FAQ -[ MOA-liveCD|http://sanbarrow.com/moa241.html] - VM-Sickbay