[linux-lvm] LVM mirrors and drive failure

[Jonathan Brassow]

On Aug 21, 2007, at 2:27 PM, Stuart D. Gathman wrote:

> The current LVM mirror code creates 3 (or more - assume just 2
> copies for discussion) pieces: copy0, copy1, log.  It is obvious what
> should and probably does happen if the PV for copy0 or copy1 goes  
> away.
> But what happens if the PV for log goes away?  Does it convert to a  
> memory
> log?  When you reboot, does it do a full sync, like with a memory log?
> Which copy is copied from and which is copied to for the sync?

Yes, it converts to an in-memory log.  Yes, you will do a full sync  
if you reboot.

We are working on code to use hot-spares.  In that case, the log  
would simply be replaced.

Also, we are working on some allocation changes so you can have a log  
and 2 copies on just two devices.

Best thing to do now is to replace the log manually if it fails.  If  
the mirror is in-sync, that will be preserved, and the mirror will  
not need to be resynced.

  brassow