Discussions specific to the VMware vSphere hypervisor
Vitaliy S.
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Re: Restore VM without breaking backup chain

Post by Vitaliy S. » Jul 20, 2016 3:05 pm

pkelly_sts wrote:Out of interest, would it make any difference to things if, instead of "full VM restore" we use a "restore vm hard disks" which retained the original shell VM/ID?
When you restore virtual disks, their CBT data will be reset, which will initiate a full data re-read for this VM.
pkelly_sts wrote:Also, talking about CBT resets etc. I thought that simply caused the original backup to be *re-read* rather than force an active full, so can't such a restore just initiate a full re-read of CBT-related data (or whatever the official task is)?
That is the case with VM replicas, where you can map VM to a VM image, but in case of backup jobs you do not select a particular VM in the backup file that can be used for mapping.

pkelly_sts
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Re: Restore VM without breaking backup chain

Post by pkelly_sts » Jul 20, 2016 3:10 pm

That was what i meant - the data re-read which is only a read, not a full re-copy is it not?

In other words, if for whatever reason we lose/reset CBT data, it only causes the original disk to be fully read, to understand its current situation etc., as opposed to fully copied to destination?
[New Sig: PLEASE get GFS tape support for incrementals!!!]

Vitaliy S.
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Re: Restore VM without breaking backup chain

Post by Vitaliy S. » Jul 22, 2016 1:42 pm

Yes, if VM ID is retained and CBT data is lost/corrupt/etc. backup job will re-read the entire image and then transfer only changed blocks (our propriety change tracking engine), though I need to double-check if it is true for restored virtual disks with new IDs.

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Re: Restore VM without breaking backup chain

Post by Zew » Jul 26, 2016 8:12 pm

Thanks for the additional info guys. Glad to see the interest this topic has spun.

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