[linux-lvm] Question on RAID integrity limitations

[Cyclic Group Z_1]

 Thank you for your reply! 
Ah ok, that makes sense. I think it is just a terminological confusion. In other contexts, restoring a lost hard drive in a degraded RAID array is called "rebuilding," but it seems here, it refers to reconstructing physical volumes that may contain corrupt data (`lvchange --rebuild`). If the replacement of a drive (in other contexts, rebuilding a degraded RAID array) is still possible through `lvconvert --replace` or `lvconvert --repair`, then my concerns are not an issue. I was worried that, by needing to turn off integrity during a rebuild, the future state of the array may be corrupt due to integrity not being active during the propagation of data to the new drive.
Regarding snapshots, that's wonderful news!
-CG

    On Monday, June 5, 2023 at 10:36:12 AM CDT, David Teigland <teigland at redhat.com> wrote:  
 
 On Sat, Jun 03, 2023 at 12:30:01AM +0000, Cyclic Group Z_1 wrote:
> The lvmraid documentation says the following: "To work around some
> limitations, it is possible to remove integrity from the LV, make the
> change, then add integrity again. (Integrity metadata would need to
> initialized when added again.) ... The following are not yet permitted
> on RAID LVs with integrity: lvreduce, pvmove, snapshots, splitmirror,
> raid syncaction commands, raid rebuild." Does this mean that RAID
> rebuilds can only be done with integrity temporarily turned off?

It refers specifically to running the command "lvchange --rebuild".  I'm
not entirely sure how important that command is, but I'd be happy to hear
more about its usefulness.

> This seems risky given that rebuilds are often when RAID arrays undergo the
> most stress and are thus vulnerable to failures/errors (namely, for
> parity RAID). Additionally, is the suggested workaround for snapshots to
> temporarily turn off integrity when taking/using snapshots?  Thank you!

Snapshots were recently enabled:
https://sourceware.org/git/?p=lvm2.git;a=commit;h=fd6e113bba5fed5ee41152cde33220294c24ce2b

Dave

  
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