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Hope that https://github.com/veeam/blksnap/issues/2 https://github.com/veeam/blksnap/issues/2 becomes available soon. It's on v7 of posting to linux-block and w

by mappu 3y ago

Hope that https://github.com/veeam/blksnap/issues/2 https://github.com/veeam/blksnap/issues/2 becomes available soon. It's on v7 of posting to linux-block and will make snapshotting available for all block devices.

apitman 3y ago
This is the first I've heard of blksnap. Looks very interesting. There's not much documentation in the repo. Am I understanding correctly that if I were to build a custom WSL kernel with those patches, I would be able to do snapshotting in WSL today? Can you give or link to a brief description of how blksnap works?
- mappu 3y ago
  You could do block device snapshotting today if you build your block devices on top of LVM. You can also somewhat do it with fsfreeze and remounting your mount point on top of a dm-snapshot target. Blksnap is better because it does not require setup in advance like LVM, and it does not require interrupting any live users like fsfreeze. It "should" just work with the live block device within the WSL distro. LWN covered the v1 posting, which is a good start: https://lwn.net/Articles/914031/ https://lwn.net/Articles/914031/ This is all somewhat future-looking, and if you only want file-level snapshotting instead of block-level, it's probably easier to try and get btrfs/bcachefs/nilfs2 instead. My WSL2 on Windows 11 shows btrfs present inside /proc/filesystems.
  - ShiftControl 3y ago
    To piggyback on this: In the 2024 century the default LVM setup still does not offer to leave some spare space on the volume group. Without that unallocated space it's impossible to create snapshots for LVs. Oh, and the change-tracking function is non existent for both LVM and dev mapper!
- ShiftControl 3y ago
  I think this doc is pretty concise: https://github.com/veeam/blksnap/blob/master/doc/blksnap.md https://github.com/veeam/blksnap/blob/master/doc/blksnap.md
ShiftControl 3y ago
Well, sadly the latest patch submission haven't got too much traction (nada, to be precise) or attention from the maintainers: https://patchwork.kernel.org/project/linux-block/cover/20240209160204.1471421-1-sergei.shtepa@linux.dev/ https://patchwork.kernel.org/project/linux-block/cover/20240...

by mappu 3y ago

apitman 3y ago

This is the first I've heard of blksnap. Looks very interesting. There's not much documentation in the repo. Am I understanding correctly that if I were to build a custom WSL kernel with those patches, I would be able to do snapshotting in WSL today? Can you give or link to a brief description of how blksnap works?

mappu 3y ago
You could do block device snapshotting today if you build your block devices on top of LVM. You can also somewhat do it with fsfreeze and remounting your mount point on top of a dm-snapshot target. Blksnap is better because it does not require setup in advance like LVM, and it does not require interrupting any live users like fsfreeze. It "should" just work with the live block device within the WSL distro. LWN covered the v1 posting, which is a good start: https://lwn.net/Articles/914031/ https://lwn.net/Articles/914031/ This is all somewhat future-looking, and if you only want file-level snapshotting instead of block-level, it's probably easier to try and get btrfs/bcachefs/nilfs2 instead. My WSL2 on Windows 11 shows btrfs present inside /proc/filesystems.
- ShiftControl 3y ago
  To piggyback on this: In the 2024 century the default LVM setup still does not offer to leave some spare space on the volume group. Without that unallocated space it's impossible to create snapshots for LVs. Oh, and the change-tracking function is non existent for both LVM and dev mapper!
ShiftControl 3y ago
I think this doc is pretty concise: https://github.com/veeam/blksnap/blob/master/doc/blksnap.md https://github.com/veeam/blksnap/blob/master/doc/blksnap.md

ShiftControl 3y ago

Well, sadly the latest patch submission haven't got too much traction (nada, to be precise) or attention from the maintainers: https://patchwork.kernel.org/project/linux-block/cover/20240209160204.1471421-1-sergei.shtepa@linux.dev/ https://patchwork.kernel.org/project/linux-block/cover/20240...