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hjensen8
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Sharing storage LUNs across clusters - is that bad idea ?

Hi,

Our current setup:
  • vSphere 5.0
  • 3 clusters, 12 hosts each. (split into 3 clusters due to different CPU generations)
  • Each cluster has approx. 20 NetApp FC LUNs assigned. (VMFS 5.0 datastores created from scratch)
I am now thinking of granting access to all 60 LUNs to all 36 hosts in the 3 cluster to ease the process of moving VMs between the clusters.
Is that a very bad idea ?
And if so, why ?
/Henrik
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elgreco81
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Hi,

The only thing I can think off (maybe not the only one out there...) is queue depths. This article gives a good glimpse at that.

http://blogs.vmware.com/vsphere/2012/07/troubleshooting-storage-performance-in-vsphere-part-5-storag...

It talks about vsphere queues, if possible, look at your storage depth queues to try to figure out if they are enough and do some monitoring afterwards to see if they need any change.

I'm not very familiar with the procedure, but hopefully this points you to the right place.

Best regards and best of lucks with those changes!!!

elgreco81

Please remember to mark as answered this question if you think it is and to reward the persons who helped you giving them the available points accordingly. IT blog in Spanish - http://chubascos.wordpress.com

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elgreco81
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Hi Henrik,

I don't see why that could be a bad idea, except for having 60 LUNS in each server which I think it could be difficult to manage. I would try to have some kind of control in order to not overuse any LUN and have some kind of control (maybe using profile driven storage or storage DRS).

If the only reason for doing this is move the VMs between clusters, woudn't be a good idea to have an NFS Datastore common to all hosts and clusters and use it as an intermediate step? Maybe this is good enough and it wouldn't have such a big impact in your enviroment.

What do you think?

Regards,

elgreco81

Please remember to mark as answered this question if you think it is and to reward the persons who helped you giving them the available points accordingly. IT blog in Spanish - http://chubascos.wordpress.com
hjensen8
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Hi elgreco81,

Thanks for your response.

I agree that managing 60 LUNs on each host is not very appealing.

Currently the size of our LUNs is 1 TBytes (goes all the way back to vSphere 3)  and we are considering consolidating the LUNs to fewer LUNs of a size of  4 TBytes and use datastore cluster to group the datastores together, based on the NetApp backup policy for each datastore.

However my main concern is that connecting 36 hosts (instead of 12 hosts) to each LUN will cause some kind of problem, similar to the SCSI-reservation problems for pre-VMFS 5 datastores?

/Henrik

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hjensen8
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Hi Sketchy00,
Thanks for the link.
I agree that sharing datastores across clusters/large number hosts might lead to same management hazzles.
But my main concern is if the configuration change will cause some kind of performance problem ?
/Henrik
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elgreco81
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Hi,

The only thing I can think off (maybe not the only one out there...) is queue depths. This article gives a good glimpse at that.

http://blogs.vmware.com/vsphere/2012/07/troubleshooting-storage-performance-in-vsphere-part-5-storag...

It talks about vsphere queues, if possible, look at your storage depth queues to try to figure out if they are enough and do some monitoring afterwards to see if they need any change.

I'm not very familiar with the procedure, but hopefully this points you to the right place.

Best regards and best of lucks with those changes!!!

elgreco81

Please remember to mark as answered this question if you think it is and to reward the persons who helped you giving them the available points accordingly. IT blog in Spanish - http://chubascos.wordpress.com
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