Re: [PLUG] Hot-swapping Linux RAID1 (was Re: Computer case)

[Julien Vehent <julien@linuxwall.info>]

On Tue, 14 Jun 2011 00:01:18 -0400, JP Vossen wrote:
> On 06/13/2011 12:51 PM, plug-request@lists.phillylinux.org wrote:
> > Date: Mon, 13 Jun 2011 12:51:46 -0400
> > From: Julien Vehent<julien@linuxwall.info>
>
> >   I've never tried hot swapping sata drives used in a linux soft 
> > raid.
> >   Might be an interesting experience though:)
>
> I have not tried this, but I'd *guess* that if you use 'mdadm'
> appropriately, it would be fine.  YMMV!
>
> Before:
> mdadm --manage $RAID --fail $DISK
> mdadm --manage $RAID --remove $DISK
>
> After hot-swap:
> sfdisk -d $GOOD_DISK | sfdisk $BAD_DISK
> mdadm --manage $RAID --add $DISK
>
> One of the tricks is to get "$RAID" & "$DISK" right.  'cat
> /proc/mdstat' can help.  And you may need to loop though the mdadm
> commands if you've got multiples of anything.
>
> See http://www.kernelhardware.org/replacing-failed-raid-drive/ for 
> more info.
>
> Let us know if this works,  :-)
> JP


I didn't know of 'sfdisk', that was the missing piece: dumping the 
partitions table and recreating it on the new drive.
With that, I don't know why it wouldn't work. I will give it a shot 
with a spare drive (that doesn't have the same geometry) and let you 
know.

I traded my 2*3.5" for 2*3.5", both 500GB and 7200rpm as well, for just 
$10 difference per drive. Not too bad of a deal :)
However, it seems that the small drives consume as much as the big one. 
I was expecting some saving there.


Julien



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