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VMware Position on vMotion of VMs with Shared RDMs and Oracle RAC
What is the current thinking on allowing vMotion of VMs running Oracle RAC with RDMs for shared storage?
Virtualization for Oracle
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I am wondering what the current thinking is on vMotion of Oracle RAC VMs which are using RDMs for shared storage. Pam Madis apparently believes, based upon this KB article, that it is now possible to enable the multi-writer flag (as opposed to the shared SCSI flag, a confusingly similar setting), on a physical RDM, and then allow VMs accessing that RDM to vMotion with no problems. I read the KB article, though, and it appears to be rather vague on the issue. Also, I did further research, and found nothing specific (other than the links above) later than 2011. If someone could pop up and let us know VMware's current position, that would be awesome. |
sullivand1
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January 17th, 2014 11:00
The exception that was created at the request of EMC is to allow the supported use of RDM-V across hosts (NOT PHYSICAL) with scsi-mwf and therefore vmotion will be supported under those limited circumstances
sullivand1
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January 17th, 2014 12:00
pRDMs will be supported in general, but not the use of vMotion when using pRDMs.
dynamox
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January 17th, 2014 12:00
"will be" or "are" supported ? Is there a technical issue with pRDM/vMotion/RAC ?
dynamox
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January 17th, 2014 12:00
pRDMs are not supported at all (for folks who want to take advantage of array features (SRDF/Timefinder) ?
jeff_browning
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January 17th, 2014 12:00
So, to clarify, the VMware supported position is that Oracle RAC can be run on a VM which is using a virtual RDM (vRDM) for shared storage with one or more Oracle RAC VMs. And vMotion of such a VM is a safe and supported operation. Correct? That is documented by the KB article referenced above. Also, physical RDMs (pRDMs) do not permit vMotion in this manner. Thus, vRDMs are required for virtualized Oracle RAC (assuming vMotion is desirable, which I would say is generally always true).
sullivand1
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January 17th, 2014 12:00
I'm OK with the statement above until the last sentence. "Thus, vRDMs are required for virtualized Oracle RAC (assuming vMotion is desirable". The recommendation is to use VMFS with Scsi-multiwrite-Flag when running RAC. vRDMs would be required if the customer wishes to use RDMs as opposed to the recommendation of VMFS
jeff_browning
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January 17th, 2014 13:00
Don:
I should have included the contextual assumption: Assuming the customer is using raw device mapping, ....
Yes, I understand the reason why VMFS is desirable.
Regards,
Jeff
sullivand1
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January 17th, 2014 13:00
pRDMs will not be supported with vMotion in general. (only vRDM)
sullivand1
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January 17th, 2014 13:00
I should more carefully phrase that pRDMs are not supported with vMotion and will not be in the future