sc_2111
Enthusiast
Enthusiast

VM allocated storage space

HI ,

I'm looking for guidelines to correctly size ESX LUN to hosts VMs.

My question is about the space we should plan for each VM , apart from the vmdk files itself.

Supposing that no snapshot are planned is it safe to allocate a space for each VM considering the sum of vmdk files and the VM's RAM ?

Thanks

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JoJoGabor
Expert
Expert

I generally add on 10% for VMware overhead to include snapshots. Bearing in mind that snapshots should not exist for any length of time, but they will be used in any backup process and potentially if using Update Manager to patch VM OSes. You will have to consider the .vswp files but this should only be used if memory is overcommitted, plus you will get vmware.logs for each VM.

You may also want to consider the likelihood that you will want to increase the VMDK. For database, file or EMail systems I am often increasing the size of the VMDK, so add an extra bit to the VMFS for expansion, unless you can plan for this in advance

Texiwill
Leadership
Leadership

Hello,

I first size my VMs, then size the LUN based on that.... The formula is:

Size of VMDKs * 2 (to include possible snapshots) + 15mbs (sundry metadata files) + sizeof Allocated Memory + 4GBs (sundry log files) = Size of VM

Size of VM * # of VMs * 1.2 = Space required for LUN with a 20% buffer.

You never want to fill a LUN past 90% and 80% is a much better number. If the VMFS is too full things stop working.

If you have a LUN size already in mind you can determine how many VMs will fit using:

Size of LUN * 0.8 / Size of VMDKS = # of VMs

Yes this sounds like a bit of empty space per LUN but it is a conservative approach for a base #.


Best regards,
Edward L. Haletky
VMware Communities User Moderator
====
Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.
Blue Gears and SearchVMware Pro Blogs -- Top Virtualization Security Links -- Virtualization Security Round Table Podcast

--
Edward L. Haletky
vExpert XIV: 2009-2023,
VMTN Community Moderator
vSphere Upgrade Saga: https://www.astroarch.com/blogs
GitHub Repo: https://github.com/Texiwill
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Cruicer
Enthusiast
Enthusiast

Are you looking for Large LUNs or small LUNs...Large meaning several VMs can reside on the same LUN or small meaning a LUN per VM or LUN per disk?

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