OlivierAlpha
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Contributor

Snapshot / RDM

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Hi,

I have an ESX 3.5 Update 2, attached to a HP SAN (EVA).

Some VM are created only with RDM disk (in physical mode) : One RDM disk for each partition

How can I create a snaphot of the C disk only ?

Thanks to help me,

Olivier

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NTurnbull
Expert
Expert

I believe you can change the RDM from physical to Virtually but as to the impact on a production env I couldn't comment.

As for persistent and non-persistent, its probably not giong to suit your needs as in order to get these settings you would have to make the disks Independent thus not allowing you to use snapshots. Also persistent just means that on a write the data gets straight to the disk but non-persistent means that when you power the VM down all the changes that were made (writes to the disk) are discarded - so when you power back up the disk would look the same as it did the last time you ppwered up/made the disk non-persistent.

You cannot create snapshots on RDMs in physical mode.

HTH

Neil

Thanks, Neil

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LarsLiljeroth
Expert
Expert

Hi

I assume the c: drive is not RDM ?!?

Not out of the box, but you could make the disk you don't want to snapshot independent/persistent.

Changes only affects on the regular drive. The independent/persistent disk will not be snapshoted, because it can't. And when you revert the snapshot only revert te regular drive


Lars Liljeroth

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NTurnbull
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Expert

Hi, sorry to say that you can't use snapshots on RDMs in physical mode it would have to be virtual mode as physical mode gives the VM direct access to the SCSI device. For more info check out the SAN Design and Deploy guide . There is some info on page 59.

Cheers!

Thanks, Neil
OlivierAlpha
Contributor
Contributor

I do not have the option "Persistent or not" with RDM in Physical mode.

So, is it possible to convert the RDM in Virtual mode. What is the risk in production activity, and, in virtual mode, wil I have the option "Persistent or not" ?

Last question (!!), with RDM in Physical mode, what happen if I create a Snapshot (does it will work ? Maybe nothings will happen ? ...)

Thanks

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NTurnbull
Expert
Expert

I believe you can change the RDM from physical to Virtually but as to the impact on a production env I couldn't comment.

As for persistent and non-persistent, its probably not giong to suit your needs as in order to get these settings you would have to make the disks Independent thus not allowing you to use snapshots. Also persistent just means that on a write the data gets straight to the disk but non-persistent means that when you power the VM down all the changes that were made (writes to the disk) are discarded - so when you power back up the disk would look the same as it did the last time you ppwered up/made the disk non-persistent.

You cannot create snapshots on RDMs in physical mode.

HTH

Neil

Thanks, Neil

View solution in original post

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LarsLiljeroth
Expert
Expert

Hi

No that is not an option with RDM.

Yes you can convert it.. but i would test it first on non prod systems.

It is not possible at all to take snapshot of a RDM in physical mode Only in Virtual mode.




Best regards

Lars Liljeroth

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// Lars Liljeroth -------------- *If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!
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LarsLiljeroth
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See this post Smiley Wink -- >> http://communities.vmware.com/message/943514#943514




Best regards

Lars Liljeroth

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If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!

// Lars Liljeroth -------------- *If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!
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OlivierAlpha
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Contributor

OK, thank you both.

Olivier

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