lvmcache man page lacks warning about unclean shutdowns

[pauldoo]

Hello,
The man page for lvmcache lacks any warnings about the behaviour of lvmcache when unclean shutdowns occur. In particular an unclean shutdown results in the entire cache being marked dirty on next boot and a lengthy write out of the entire cache begins. This occurs regardless of the mode (writethrough or writeback).

This behaviour has been raised previously on upstream linux-lvm and dm-devel mailing lists, but the situation has not changed since at least 2014. I don't expect the implementation to be changed therfor, only that the documentation be updated to highlight this behaviour.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: lvm2 2.03.07-1ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Sun May 10 20:55:55 2020
SourcePackage: lvm2
UpgradeStatus: Upgraded to focal on 2020-04-24 (15 days ago)

[pauldoo (paul-richards)]

I raised this on linux-lvm mailing list recently, and included links there to previous posts of this problem: https://www.redhat.com/archives/linux-lvm/2020-May/msg00000.html