Host-based backup of Microsoft Hyper-V VMs.
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madshark
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Convert Physical Sector Size of 512 to 4096

Post by madshark »

Hi, if I have a VM that was created some time ago and / or with a physical sector size of 512k then is there a way I can use Veeam to convert it to have a physical sector size of 4k?

The scenario is migrating VMs of an older legacy Hyper-V platform or VMware platform. The new platform is modern Hyper-V with S2D and 4k Drives. I want to optimize the VMs and not take a performance hit of writes, etc.

I can change the migrated VHDX's physical sector size from 512 to 4096, but that doesn't change the file system (when checking with 'fsutil fsinfo ntfsinfo c:'). I don't want to re-install the OS and format with the 4k sector size and so wondering if anyone has found a 'clever' way to do this using Veeam replication or backup/restore? For data disks I can just add a new VHDX with the correct sector size and copy data over.

Many thanks
HannesK
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Re: Convert Physical Sector Size of 512 to 4096

Post by HannesK »

Hello,
and not take a performance hit of writes, etc.
just curious... how much performance hit in per cent do you see / expect?

I cannot imagine how a backup software could change the file system format. There are also side-effects depending on the operating system, UEFI and MBR vs. GPT disks. So I would go for fresh installation (well, I would not do it because I did not find enough evidence to justify it)

Best regards,
Hannes
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