From: Neil Brown <neilb@suse.de>
To: "Keith ." <lukano@gmail.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: Shrink mdadm RAID5 from 6 disks to 5?
Date: Fri, 21 May 2010 08:32:41 +1000 [thread overview]
Message-ID: <20100521083241.43755d02@notabene.brown> (raw)
In-Reply-To: <AANLkTimn5ieodsVPsZY022b7VAnfFNARyb3sQn2LMp7u@mail.gmail.com>
On Thu, 20 May 2010 15:42:23 -0600
"Keith ." <lukano@gmail.com> wrote:
> Thanks for the quick reply Neil,
>
> I tried the suggested syntax, excluding the array-size in order to
> have mdadm give me the value - but it did not. I also tried grabbing
> the current array size from df, but I got an error about being unable
> to change array size in the same operation.
>
> So just to confirm I'm understanding you correctly ; mdadm -G
> /dev/md127 --raid-devices 5 --backup=/root/backup - should generate
> an error that provides the array-size value?
Yes.
Actually, you do probably need to change the size first:
mdadm --grow /dev/md127 --array-size=xxxxx
then once you are sure you haven't lost you data, change the number of
devices.
It might help if you ran the commands with "-v" and reported all the
messages generated, and any kernel log messages.
And maybe
cat /proc/mdstat
just to give us some more context..
Maybe you have a write-intent-bitmap attached to the array. You cannot
reshape an array with one of those attached.
NeilBron
>
> On Thu, May 20, 2010 at 3:34 PM, Neil Brown <neilb@suse.de> wrote:
> > On Thu, 20 May 2010 07:45:23 -0600
> > "Keith ." <lukano@gmail.com> wrote:
> >
> >> Does mdadm 3.1.x not support shrinking the number of disks in a RAID5 array?
> >>
> >> I have successfully converted my 6x1.5tb RAID6 array to a 6x1.5tb
> >> RAID5 array. The issue that I now face is that one of those 6 drives
> >> is failed / removed, and as a result - the new RAID5 array is down
> >> it's parity drive.
> >>
> >> I knew I was short a disk when I started the process, but I was under
> >> the assumption that mdadm now supported shrinking of RAID5/6 arrays.
> >> Am I mistaken, or can anyone throw some suggestions at me so I can
> >> give it a try?
> >
> > It should work.
> >
> > mdadm -G /dev/mdX --raid-devices 5 --array-size=XXXXX
> > --backup=/root/backup-file
> >
> > If you don't give the 'array-size' value mdadm will tell you what it has to
> > be. You need to be sure that all your data is already within that space.
> >
> > NeilBrown
> >
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next prev parent reply other threads:[~2010-05-20 22:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-20 13:45 Shrink mdadm RAID5 from 6 disks to 5? Keith .
2010-05-20 21:34 ` Neil Brown
2010-05-20 21:42 ` Keith .
2010-05-20 22:32 ` Neil Brown [this message]
[not found] ` <AANLkTikQcA98OzjFn93X8ChJanHMLTIdrvrIEMQAU4lA@mail.gmail.com>
[not found] ` <AANLkTilJqmd9jwNSdlBxA4G07bB7RLB6XR0AwqFhe5uk@mail.gmail.com>
2010-05-30 22:54 ` Keith .
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