Re: replacing drives

[Robin Hill <robin@robinhill.me.uk>]

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On Wed May 08, 2013 at 04:19:33PM +0200, Roberto Nunnari wrote:

> Robin Hill wrote:
> > On Fri May 03, 2013 at 06:28:02PM +0200, Roberto Nunnari wrote:
> > 
> >> Robin Hill wrote:
> >>> The safest option would be:
> >>>  - add in the new disks
> >>>  - partition to at least the same size as your existing partitions (they
> >>>    can be larger)
> >>>  - add the new partitions into the arrays (they'll go in as spares)
> >>>  - grow the arrays to 4 members (this avoids any loss of redundancy)
> >>>  - wait for the resync to complete
> >>>  - install grub/lilo/syslinux to the new disks
> >>>  - fail and remove the old disk partitions from the arrays
> >>>  - shrink the arrays back down to 2 members
> >>>  - remove the old disks
> >>>
> >>> Then, if you're keeping the same number of partitions but increasing the
> >>> size:
> >> Ok.. got here.
> >>
> >>>  - grow the arrays to fill the partitions
> >>>  - grow the filesystems to fill the arrays
> >> Now the scary part.. so.. here I believe I should give the following 
> >> commands:
> >>
> >> mdadm --grow /dev/md0 --size=max
> >> mdadm --grow /dev/md1 --size=max
> >> mdadm --grow /dev/md2 --size=max
> >>
> > Yep, that's right. Make sure they've actually grown to the correct size
> > before you progress though - I have had one occasion where using
> > --size=max actually ended up shrinking the array and I had to manually
> > work out the size to use in order to recover. That was using an older
> > version of mdadm though, and I've not seen it happen since.
> > 
> >> and after that
> >>
> >> fsck /dev/md0
> >> fsck /dev/md1
> >> fsck /dev/md2
> >>
> > You'll need 'fsck -f' here to force it to run.
> 
> humm.. as /dev/md0 is mounted on / I probably should boot from a cd, and 
> run fsck and resize2fs from there.. maybe using UUIDs, right?
> 
You can just skip the fsck and run resize2fs - it'll work fine on a
mounted filesystem. It'll probably be safer to do it offline though.

Cheers,
    Robin
-- 
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    ( ' }     |       Robin Hill        <robin@robinhill.me.uk> |
   / / )      | Little Jim says ....                            |
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