[linux-lvm] Re: Software raid on top of lvm logical volume

Peter T. Breuer ptb at lab.it.uc3m.es
Thu Oct 28 19:17:11 UTC 2004

Luca Berra <bluca at comedia.it> wrote:
> On Thu, Oct 28, 2004 at 08:01:27AM +0200, Eric Monjoin wrote:
> >md9 : active raid1 emcpowerd1[2] [dev e8:e1][0]
> >      42829184 blocks [2/1] [U_]
> >      [>....................]  recovery =  1.4% (630168/42829184) 
> >finish=68.1min speed=10315K/sec
> this is a problem with linux md raid. it does not support fast resync
> with a bitmap of changed sectors, there is a project to implement it,
> but it is not yet in the standard kernel.
> look on the linux-raid mailing list archives for something called 'fast
> raid 1'.

   fr1.sf.net (also fr5.sf.net may be of interest).

   and http://www.it.uc3m.es/ptb/fr1

(yes, I am the author). Those are for 2.4 kernels. A version fo fr1
for 2.6 kernels with additional ondisk bitmaps has been done by Paul
Clements, the linux nbd maintainer, and patches by him are around.

I should look them up and merge the two .. bids accepted!

> i do not believe you would have any advantage in stacking md above lvm
> anyway.

That is right. In fact it sounds downright risky to me.


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