[mythtv-users] Linux software raid question

kim Gross kgross at jensalt.com
Fri Jun 6 16:19:49 UTC 2008

> Thanks for the link.  Much more helpful than just using the mdadm man
> page - wish I had found it when I set up my first software raid (very
> trial-and-error).
> One question - I have read both that it is and is not possible to move
> a raid-5 to larger disks by replacing them one-by-one.  I would think
> this sort of procedure would be desirable for us myth users who
> consistently seem to build "budget-conscious" machines and then run
> out of space for our favorite shows.
> The wiki page on "Growing" makes the following statement:
> "It is possible to move whole RAID array to bigger disc drives by
> replacing one by one."
> which is followed by:
> "

I have done it and it worked fine.  I started out my array with 4 250 
gig drives and 1 200 gig drive.  When the array was first set-up all 
drives were partitioned at 200 gig, and I was going to do a second array 
of the extra 50 gigs on the other drives.  About a week after I set up 
the array I got a 250 gig drive to replace the 200, so I partitioned it 
to the full 250, removed the 200 from the array and added the 250, 
rebuilt the array.  Then I repartitioned the other drives and rebuilt 
the array one at a time.  After all drives were repartitioned and the 
array rebuilt, I grew the array without any problems.  I don't remember 
what version of mdadm I used, but this was about 1 year ago under Fedora 
6 I believe.

So it is very possible, I don't know what the odds are of a problem, but 
in my case it worked great.  If you were replacing all drives though, 
you could keep the original array drives, and possible set up the old 
array if anything went wrong.  Just remove one drive, add newer larger 
drive, rebuild array, remove next drive, rebuild, until you have all 
drives replaced.  Then grow the array.  If something goes wrong, it will 
take some work, but you should be able to start with the first drive you 
removed and put the other drives back in and start up the original array 
to get data off of it.


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