FreeNAS to Store VHDs for Hyper V

[Tom Murphy]

Hello all, questions like this keep me awake at night so though I would ask it!

If I use FreeNAS as storage for my Hyper V VHD/VHDx virtual disks (be it iScsi or a folder share \\servername\VHDs) and the VHDs are then formatted in NTFS, the data stored on the NTFS VHDs is still susceptible to "bit-rot" or data corruption as if they were a physical disk - Correct? All ZFS will do in this case is ensure that the VHD files will be 100% ok but not the Data in them that the Virtual OS has written to the VHD disk?

Is that a correct assumption?

Thanks,
Tom

 

[Nick2253]

No, you misunderstand bit rot. Bit rot is not a virtual or theoretical problem, it's a physical problem. What happens is that data that's written on a physical device is corrupted in some way, and the file system doesn't know about it. Typically, bit rot refers to magnetic sectors that lose their magnetic orientation over time; in other words, the magnetic field "rots" away.

ZFS ensures that the data that's written to the physical disks, whether it's a file or an iSCSI volume (whatever the format), will be the same as the data that is read from the disk.

 

[Tom Murphy]

Perfect, thank you Nick! :)

 

[Nick2253]

Happy to help! Let us know if you need anything else.

 

[Stux]

And ZFS snapshots can protect file systems from corruption.

So if your NTFS zvol corrupted, you could restore/mount a snapshotted clone and restore files.