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synestine@sh.itjust.works ⁨1⁩ ⁨week⁩ ago

LVM itself does not provide redundancy, that’s RAID. LVM is often used on top of a RAID device. If your boot drive fails, LVM itself won’t save you, RAID (software RAID 1 is really common for a boot drive) can.

LVM can be used to seamlessly move data between physical volumes. You can add a new PV to the VG and move extents between LVs. I’ve used it to love-migrate to a larger drive that way. Once the physical extents have been moved to the new PV, you can reduce the old PV and then remove the old disk.

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kumi@feddit.online ⁨1⁩ ⁨week⁩ ago

LVM itself does not provide redundancy, that’s RAID.

I think this is potentially a bit confusing.

LVM does provide RAID functionality and can be used to set up and manage redundant volumes.

See --type and --mirror under man 8 lvcreate.

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- synestine@sh.itjust.works ⁨5⁩ ⁨days⁩ ago
  Correct, however basically no one uses that. The MD (RAID) devices are much more common for that, including under boot drives.
  
  See comparison on ServerFault.
  
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Cenzorrll@lemmy.world ⁨1⁩ ⁨week⁩ ago
I try keep my data drives and boot drives separate on my servers, I make sure I can rebuild the server relatively easily so no matter what happens I can get back up and running. In my research on LVMs I wasn’t seeing anything saying you could just move the drives to a new setup, that you had to export and import first. In the case of a suddenly dead boot drive, I wouldn’t be able to do that. I did see some steps for backing up an LVMs metadata and recovering from that, so I might be sure I do that at some point, but another user said that modern distros should be able to scan for LVMs without issue, which is not what I found in my quick test in my setup. So I’ll be checking that out in a more modern setup to double check.

From what I was reading, recovering from corrupted metadata is not something I want to do. I’d rather not use LVM if that’s what’s required if I can’t just move the drives to a new server, as nice as it would be to resize filesystems on a whim.

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- synestine@sh.itjust.works ⁨1⁩ ⁨week⁩ ago
  If personal anecdote is good for anything, I’ve been using LVM on top of software RAID on Linux for close to 20 years now without ever losing a volume. The last time I lost data was on ReiserFS 3. Like I said, LVM does not protect against drive failure itself. That’s why I use RAID underneath. I’ve got my OS disk to protect against failures like that. Also frequent and verified backups of my data files to make sure that is protected.
  
  And yes, modern (still supported) distros can scan LVM PVs on boot without issue.
  
  LVM Physical Volumes (PV) can be moved between Linux machines without issue (I’ve done that several times), it’s not like hardware RAID where you have to have the same controller on both machines. Nothing I’ve done has ever required LVM metatata export/import.
  
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