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1,598 Views 9 Replies Last post: Mar 1, 2010 5:28 AM by depping RSS
rManic Expert
rManic
318 posts since
Oct 7, 2009
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Feb 28, 2010 6:02 AM

multiple VMFS datastore

is it possible to create multiple datastore on a single LUN or on a local RAID volume?.

 

regards

Manic

amvmware Expert
amvmware
389 posts since
Feb 26, 2007
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1. Feb 28, 2010 6:55 AM in response to: rManic
Re: multiple VMFS datastore

It is not advised to do this - you should have a 1:1 ratio between the datastore and a LUN.

 

When you install ESX 4.0 it creates a local VMFS datastore to host the system console.

rManic Expert
rManic
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2. Feb 28, 2010 11:03 AM in response to: amvmware
Re: multiple VMFS datastore

thanks for u r update.

 

the reasion why I am asking this question is, most of clustering filesystem like NTFS are giving option to create multiple partition on same physical disk or lun. why VMware not giving this option?.

 

is there any technical reasion behind?.

 

regards

Manic

Regards Manic
amvmware Expert
amvmware
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3. Feb 28, 2010 11:36 AM in response to: rManic
Re: multiple VMFS datastore

NTFS is not a cluster aware file system - so a single server is the owner of that partition . So only a single server will have IO access to the NTFS partition.

 

VMFS is cluster aware - so multiple servers will have IO access to the partition - for performance reasons it is recommended to deploy a single VMFS datastore on a single storage lun to ensure the LUN does not become a performance bottleneck.

depping Champion VMware Employees User Moderators vExpert
depping
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4. Feb 28, 2010 11:46 AM in response to: rManic
Re: multiple VMFS datastore

yes you can but we don't recommend it. the reason for not recommending this is lun locking. when we temporarily lock a volume to do metadata updates we lock the FULL LUN and not only the partition. So when you have 2 VMFS volumes on a single LUN chances are bigger you will run into conflicts. Avoid it!

 

 

 

 

Duncan

VMware Communities User Moderator | VCP | VCDX

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rManic Expert
rManic
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Oct 7, 2009
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5. Feb 28, 2010 7:45 PM in response to: depping
Re: multiple VMFS datastore

Hi Duncan

 

Thanks for your info. I am not going to do it. shake of my knowledge I asked this.

What is the use of the following option(show in the screen shot) when you create VMFS datastore?.

 

 

regards

Manic

Regards Manic
rManic Expert
rManic
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Oct 7, 2009
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6. Feb 28, 2010 8:00 PM in response to: amvmware
Re: multiple VMFS datastore

dear amwmware

 

thanks for you reponse. NTFS is also cluster aware filesystem. We can also do clustering in windows with shared LUN formatted with NTFS using Microsoft Cluster Shared Volumes (CSV).

 

regards

Manic

Regards Manic
amvmware Expert
amvmware
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7. Mar 1, 2010 1:14 AM in response to: rManic
Re: multiple VMFS datastore

NTFS is not by default a cluster aware file system - yes using windows 2008 and hyper-v and failover clustering you have an option to enable microsoft clustered volumes - this is to deal with a specific issue that MS had, that meant you had to have each VM in its own dedicated lun as NTFS was not a cluster aware file system or buy a third party cluster aware file system from the likes of sanbolic.

 

We should also be clear that clustered volumes are meantt for one particular scenarion only  - they cannot be used for other requirements such as sharing data or files - it is only for VM's.

 

I have spoken with MS and they recomend best practise is to follow the same storage design principles for cluster aware file systems as for VMFS ie one datastore or volumer per lun.

rManic Expert
rManic
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Oct 7, 2009
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8. Mar 1, 2010 4:14 AM in response to: amvmware
Re: multiple VMFS datastore

thank you so much for your detailed explanation.

regards

Manic

Regards Manic
depping Champion VMware Employees User Moderators vExpert
depping
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Jan 17, 2005
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9. Mar 1, 2010 5:28 AM in response to: rManic
Re: multiple VMFS datastore

VMware is just providing you with an option to do it. Although we, Professional Services, don't agree that you should ever do this... the developers did give you the opportunity to do it. I would always use "Max" when creating a VMFS volume.

 

 

 

 

Duncan

VMware Communities User Moderator | VCP | VCDX

-

Now available: Paper - vSphere 4.0 Quick Start Guide  (via amazon.com) | PDF (via lulu.com)

Blogging: http://www.yellow-bricks.com | Twitter: http://www.twitter.com/DuncanYB

Duncan | Yellow-Bricks.com | Author of the vSphere 5.0 Clustering Deepdive

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