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cdufres
Contributor
Contributor

vSphere 5 LUN/datastore sizing.

I am working on setting up our vSphere 5 environment.  With vSphere 5 you can go > the 2TB VMFS datastore size that you were capped at with in 4.x, etc.  What size datastores are people using and whats a good way to determine the correct size?

My environment:
Hosts: 
I will be using 6 hosts (2 CPUS per w/ 6 cores per) = 72 cores.  192GB RAM per host = 1152GB RAM.
SAN:
VNX5500 with 35TB storage.  I have 22TB left for my virtual environment.  This is tiered so it has a mix of SSD, SAS, NLS drives.
I saw someone use a formula someplace that looked like this: 
(disk pool capacity – 10% free space) / total processors = datastore size
Does that look right?  I may setup different levels of pools on the VNX, maybe gold/silver/bronze (which would basically be aimed at a SLA).  So using this formula I would have a gold pool of lets say 10TB.
So thats (10TB - 10%) = 9TB (9000) / 72 = 125 so is that 1.25TB per datastore?  And I would end up with ~7 datastores on 10TBs of space?  Since VMware is aiming at easier managment through few objects, being able to go over 2TB per VMFs 5 DS now this doesn't look right to me?
Any help at all sizing my datastores would be much appreciated.

Thanks,

Chadd

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aravinds3107
Virtuoso
Virtuoso

Refer the below article which are relevant to VMFS5

http://blogs.vmware.com/vsphere/2011/07/new-vsphere-50-storage-features-part-1-vmfs-5.html

http://www.vmware.com/files/pdf/techpaper/Whats-New-VMware-vSphere-50-Storage-Technical-Whitepaper.p...

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=200381...

If you find this or any other answer useful please consider awarding points by marking the answer correct or helpful |Blog: http://aravindsivaraman.com/ | Twitter : ss_aravind
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VirtuallyMikeB

Good day,

This is an oft-posted topic in the VMTN forums and beyond.  There are probably as many answers as there are folks asking the question.  I like to look to those trusted in the community for answers, so let me point you towards Duncan Epping and Gabe from Gabe's Virtual World.  Their two posts about this topic give two expert opinions on the matter and should give you a good place to start.

http://www.yellow-bricks.com/2009/06/23/vmfslun-size/

http://www.gabesvirtualworld.com/storage-how-to-size-your-luns/

Epping notes two general questions to ask about the environment before continuing:

  • What’s the maximum amount of VMs you’ve set for a VMFS volume?
  • What’s the average size of a VM in your environment? (First remove the really large VM’s that typically get an RDM.)

and uses the following formula:

round((maxVMs * avgSize) + 20% )

where maxVMs is the maximum amount of VMs you want per datastore and avgSize is, of course, the average size of a VM.

Gabe uses an average number of .vmdks per datastore, also based on the average size of each VM.  This can be an important design consideration if you split up your .vmdks into their respective datastores, such as OS, data, vswap, etc.

I also worked with one fellow who liked to use nice, (large) round numbers for all his datastores.  The smallest were 500GB, then 1 TB, 1.5 TB, etc.  Then he'd split up .vmdks as mentioned above, for OS, data, vswap, paging, etc.

One important thing to keep in mind is your I/O - too many .vmdks per datastore that are too active could lead to storage latency issues.

Cheers,

Mike

http://VirtuallyMikeBrown.com

https://twitter.com/#!/VirtuallyMikeb

http://LinkedIn.com/in/michaelbbrown

Message was edited by: VirtuallyMikeB

----------------------------------------- Please consider marking this answer "correct" or "helpful" if you found it useful (you'll get points too). Mike Brown VMware, Cisco Data Center, and NetApp dude Sr. Systems Engineer michael.b.brown3@gmail.com Twitter: @VirtuallyMikeB Blog: http://VirtuallyMikeBrown.com LinkedIn: http://LinkedIn.com/in/michaelbbrown
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