jedijeff
Enthusiast
Enthusiast

Can you share a datastore across multiple Clusters?

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I was wondering if you can share a datastore across multiple clusters without any locking issues. Single Datacenter, but multiple Clusters(Esxi 4 and 5). Luns to be shared across Clusters are VMFS3.

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CHogan
VMware Employee
VMware Employee

Some pros and cons can be found in these articles...

http://www.yellow-bricks.com/2010/02/05/storage-masking/

http://www.yellow-bricks.com/2012/09/21/say-goodbye-to-the-transfer-lun-aka-swing-lun-aka-stepping-s...

Concerns would be an APD condition impacting more than 1 cluster, as well the ability for said LUN to perform when accessed from multiple hosts from multiple clusters.

The original use case as a swing-LUN for migrating VMs between clusters but which is no longer necessary in vSphere 5.1 with enhanced vMotion functionality.

HTH

Cormac

http://cormachogan.com

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a_p_
Leadership
Leadership

Yes this is possible. You can even vMotion VMs between clusters, provided the hosts are compatible.

André

jedijeff
Enthusiast
Enthusiast

I thought so. I had our SAN vendor say they would be corruption---basically had the mirror the cluster format on our SANs and when mapping luns between them it errored. I explained that esx would take care of the locking issues. Just thought I would check. Thanks,,,

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chriswahl
Virtuoso
Virtuoso

Locking concerns are usually more around the quantity of VMs running on a datastore and if VAAI is supported, not how many clusters / hosts are presented. Your vendor may be thinking more around something like Windows failover clustering, which only allows one node to actively use the disk at once.

Note: Without VAAI, the entire LUN is locked when a write needs to occur. With VAAI, the ATS primitive allows you to do sub-LUN locks for just that VM.

VCDX #104 (DCV, NV) ஃ WahlNetwork.com ஃ @ChrisWahl ஃ Author, Networking for VMware Administrators
jedijeff
Enthusiast
Enthusiast

Yes we have 1 SAN that suppors ATS,,the other will after a firmware upgrade. Excited to start using it. Will make a big difference, though we dont see a lot of reservation problems. thanks!

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CHogan
VMware Employee
VMware Employee

Some pros and cons can be found in these articles...

http://www.yellow-bricks.com/2010/02/05/storage-masking/

http://www.yellow-bricks.com/2012/09/21/say-goodbye-to-the-transfer-lun-aka-swing-lun-aka-stepping-s...

Concerns would be an APD condition impacting more than 1 cluster, as well the ability for said LUN to perform when accessed from multiple hosts from multiple clusters.

The original use case as a swing-LUN for migrating VMs between clusters but which is no longer necessary in vSphere 5.1 with enhanced vMotion functionality.

HTH

Cormac

http://cormachogan.com
jedijeff
Enthusiast
Enthusiast

Thanks, I forgot about that. I assume on non-shared storage the data is simply moved through the vmotion network?

Also these clusters are 4.1 and 5.1,,,so i dont think this will work entirely for me. therefore i may have to use a swing lun.

A

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CHogan
VMware Employee
VMware Employee

Yes - its only available in 5.1.

There is a great deep-dive on it here - http://frankdenneman.nl/vmotion/vsphere-5-1-vmotion-deepdive/

http://cormachogan.com
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TedH256
Expert
Expert

Yes - a datastore can be shared at the storage level across multiple clusters - this is not dependant on 5.1, we have been able to do this forever.

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jedijeff
Enthusiast
Enthusiast

Thanks everyone!

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