From: NeilBrown <neilb@suse.de>
To: Errol Neal <eneal@businessgrade.com>
Cc: Linux-RAID <linux-raid@vger.kernel.org>
Subject: Re: auto assemble in read-only mode?
Date: Wed, 8 Oct 2014 10:33:16 +1100 [thread overview]
Message-ID: <20141008103316.5ff79105@notabene.brown> (raw)
In-Reply-To: <1412685094488232500@businessgrade.com>
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On Tue, 7 Oct 2014 08:31:34 -0400 Errol Neal <eneal@businessgrade.com> wrote:
> On Tue, 10/07/2014 03:15 AM, NeilBrown <neilb@suse.de> wrote:
> > On Tue, 7 Oct 2014 02:56:31 -0400 Errol Neal <eneal@businessgrade.com> wrote:
> >
> > > On Mon, 10/06/2014 09:06 AM, Errol Neal <eneal@businessgrade.com> wrote:
> > > > hi folks. is it possible to assemble an md device in read-only mode?
> > > > after an array has been assembled, I know I can mark it as readonly with --misc -o /dev/md0 for example, but only after its been assembled it seems..
> > > >
> > >
> > > Hi again. No thoughts here?
> >
> > Not even 18 hours since you last asked - what do you thing this is? The
> > Internet :-)
>
> HAHA. I tend to feel ignored on large mailing lists lol. Need to see my therapist again ;)
>
> >
> > > I'm need to run a RAID1 device on two independent nodes (shared storage) and I'd like to assemble the device on the "slave" node in read-only mode to prevent any sync actions and etc.
> >
> > Did you try adding the "--readonly" option to your --assemble command?
> > (Always best to report everything you tried and how it failed - requires less
> > guess work).
>
> I did that previously and mdadm told me that "option --readonly not valid in assemble mode". E.g. "mdadm --assemble --scan --readonly".
That tells me use are using a version of mdadm earlier than 3.3.
"--assemble --readonly" support was added for 3.3.
NeilBrown
> The readonly flag seems like it can only be used after a device has been assembled. So for example, after the device has been assembled, I can
> run mdadm --misc -o /dev/md0 but that is not always safe for my use case.
>
>
>
> > I hope you don't expect too much of a filesystem mounted from such an array
> > while the other node is writing to the array...
> >
>
> I don't. It will be read-only until the pacemaker RA promotes the slave.
> --
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prev parent reply other threads:[~2014-10-07 23:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-06 13:06 auto assemble in read-only mode? Errol Neal
2014-10-07 6:56 ` Errol Neal
2014-10-07 7:15 ` NeilBrown
2014-10-07 12:31 ` Errol Neal
2014-10-07 23:33 ` NeilBrown [this message]
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