VMware

This Question is Possibly Answered

1 "correct" answer available (10 pts) 2 "helpful" answers available (6 pts)
3 Replies Last post: May 14, 2008 10:32 AM by Jasemccarty  

VMs per Datastore Limit with VMFS and NFS? posted: May 14, 2008 2:24 AM

Click to view ktenzer's profile Lurker
ktenzer
1 posts since
May 14, 2008
My questions is as follows:

What is the best practice for the Maximum Number of VMs one should configure in a given datastore when using VMFS? If the VMs are not servers but rather desktop machines what is the maximum number? Also the same two questions if that datastore is NFS?

I have heard that due to VMFS locking the recommended maximum number of VMs in a server ENV is 20 per datastore and in a Desktop ENV (where all VMs are windows XP workstations) it is 40. The explanation I have heard for these limitations is VMFS SCSI 2 locking and the overhead involved. Since NFS does not have locking issues like SCSI, I would think the NFS limitations would only be based on number of IOs and Bandwidth.

Look forward to hearing what you guys think and what you recommend also any links to documentation would be greatly appreciated :)

Thanks in Advance,

Keith Tenzer

Re: VMs per Datastore Limit with VMFS and NFS?

1. May 14, 2008 4:16 AM in response to: ktenzer
Click to view wgardiner's profile Hot Shot
wgardiner
164 posts since
Mar 24, 2008

There's an interesting article that was just released discussing this:

http://www.gabesvirtualworld.com/?p=68

Re: VMs per Datastore Limit with VMFS and NFS?

2. May 14, 2008 10:24 AM in response to: ktenzer
Click to view kjb007's profile Guru vExpert
kjb007
5,618 posts since
Sep 18, 2006

The SCSI reservation and release is part of it, as is also that the I/O you get is per the LUN. Both make up the general recommendation to host around 20 servers per LUN. Now, you can have more than one LUN in your datastore, which isn't usually the recommended configuration. NFS does not adhere to the same recommendation, for the reasons you mentioned, file-level locking and I/O and bandwidth play a bigger part there. Also, NFS will not allow you to multipath your connections either, so you'll reach a theoretical max there as well. So, yes, you can have larger datastores and more VMs in NFS, but you will reach a max there as well, but that number is usually higher that as iSCSI or FC.

-KjB

Re: VMs per Datastore Limit with VMFS and NFS?

3. May 14, 2008 10:32 AM in response to: kjb007
Click to view Jasemccarty's profile Champion vExpert
Jasemccarty
3,826 posts since
Apr 5, 2005

I've always been amazed that we can get around 70-90 vmdk's (different guests) per LUN.

Of course, we aren't using NFS... But with 10GigE out there, who knows...

Jase McCarty
http://www.jasemccarty.com
Co-Author of the upcoming book, Essential VMware ESX

Actions

VMware Beta Programs

Want to be Considered for Future Beta Programs?

Learn More

VMware Developer

Download SDKs, APIs, videos,
training, and more in the Developer community.

Learn More

Developer
Sample Code

Increase your developer productivity with VMware API sample code.

Learn More

VMworld
Sessions & Labs

Online access to the latest VMworld Sessions & Labs and online services.

Learn more

Purchase PSO Credits Online

Purchase credits to redeem training and consulting services online.

Buy Now

Community Hardware Software

View reported configurations or report your own.

Learn More

Only VMware ... Delivers Nexus 1000V

Ensure consistent, policy-based network capabilities to virtual machines across your data center.

Learn More

Communities