[linux-lvm] Fun and games with mirroring

Stuart D Gathman stuart at bmsi.com
Wed May 23 22:39:30 UTC 2012

On 05/23/2012 03:07 PM, Les Mikesell expounded in part:
> I thought these days you could raid the whole disk and put partitions 
> on the raid, although I've never done it that way. I have 2 complaints 
> about MD. One is that it doesn't handle errors/retries on members very 
> well - it will kick members that are perfectly fine running standalone 
> or as the last remaining member, and the other is that partitions over 
> 2TB need a new format that the kernel doesn't auto-detect. Much of the 
> reason I liked MD in the first place was its ability to assemble 
> things correctly at boot regardless of the drive's physical attachment 
> or location. 
You can raid the whole disk.  But having smaller partitions makes it 
easier to distribute them over odd numbers of disks.  Back when I ran 
AIX, you could add a disk of any size to the VG, and mirrored LVs would 
allocate LPs from physically separate PPs.   You never had to worry 
about matching disk sizes.  With MD, you can also add odd disk sizes and 
fully use them, but you have to do it manually, and more solutions are 
available with smaller partitions.  (But having too many is too tedious.)

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