Host-based backup of Microsoft Hyper-V VMs.
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barrett27
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Entire virtual disk must be read

Post by barrett27 »

Hello,
I have a problem with 3 big virtual machine on Hyper-V, because when their disks are resized, the backup job reads the entire virtual disk and it takes too long to finish, so the job exceeds the backup window resulting in a failed state

Is it Hyper-V that resets CBT every time that a disk is modified? Is there a way to prevent this beahviour? Or I have to tell to the customer to not modify the disk anymore :) ?

Thank you

db
PetrM
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Full Name: Petr Makarov
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Re: Entire virtual disk must be read

Post by PetrM »

Hello,

The CBT reset is initiated by Veeam to prevent possible data corruption and it is not possible to prevent this behavior. The data consistency and smooth restore are the highest priorities in any case. I suppose the customer could extend backup window before disk resize.

Thanks!
barrett27
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Re: Entire virtual disk must be read

Post by barrett27 »

Hi Petr,
unfortunately, the backup cannot runs during business hour because affects the server performances, so even occasionally, the backup window cannot be extended.

db
PetrM
Veeam Software
Posts: 3264
Liked: 528 times
Joined: Aug 28, 2013 8:23 am
Full Name: Petr Makarov
Location: Prague, Czech Republic
Contact:

Re: Entire virtual disk must be read

Post by PetrM »

Maybe you can consider to run it on weekend or apply storage latency control to reduce load during backup. Also, you can deploy off-host proxy to shift processing from the Hyper-V host to a dedicated machine or use "dedupe-friendly" compression or disable compression in backup job settings to decrease CPU consumption on host.

Thanks!
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