From: NeilBrown <neilb@suse.de>
To: Alexander Lyakas <alex.bolshoy@gmail.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: MD devnode still present after 'remove' udev event, and mdadm reports 'does not appear to be active'
Date: Tue, 30 Aug 2011 07:25:57 +1000 [thread overview]
Message-ID: <20110830072557.428fab35@notabene.brown> (raw)
In-Reply-To: <CAGRgLy4K-sFpeHhu_f+7-F8Fa_L1OP7ki0X-_9858BbBQrnWOA@mail.gmail.com>
On Mon, 29 Aug 2011 20:17:34 +0300 Alexander Lyakas <alex.bolshoy@gmail.com>
wrote:
> Greetings everybody,
>
> I issue
> mdadm --stop /dev/md0
> and I want to reliably determine that the MD devnode (/dev/md0) is gone.
> So I look for the udev 'remove' event for that devnode.
> However, in some cases even after I see the udev event, I issue
> mdadm --detail /dev/md0
> and I get:
> mdadm: md device /dev/md0 does not appear to be active
>
> According to Detail.c, this means that mdadm can successfully do
> open("/dev/md0") and receive a valid fd.
> But later, when issuing ioctl(fd, GET_ARRAY_INFO) it receives ENODEV
> from the kernel.
>
> Can somebody suggest an explanation for this behavior? Is there a
> reliable way to know when a MD devnode is gone?
run "udevadm settle" after stopping /dev/md0 is most likely to work.
I suspect that udev removes the node *after* you see the 'remove' event.
Sometimes so soon after that you don't see the lag - sometimes a bit later.
NeilBrown
>
> Thanks,
> Alex.
> --
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next prev parent reply other threads:[~2011-08-29 21:25 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-29 17:17 MD devnode still present after 'remove' udev event, and mdadm reports 'does not appear to be active' Alexander Lyakas
2011-08-29 21:25 ` NeilBrown [this message]
2011-08-30 15:18 ` Alexander Lyakas
2011-08-31 0:54 ` NeilBrown
2011-09-01 21:18 ` Alexander Lyakas
2011-09-13 8:49 ` Alexander Lyakas
2011-09-21 5:03 ` NeilBrown
2011-09-23 19:24 ` Alexander Lyakas
2011-09-25 10:15 ` NeilBrown
2011-10-11 13:11 ` Alexander Lyakas
2011-10-12 3:45 ` NeilBrown
2011-10-19 12:01 ` Alexander Lyakas
2011-10-19 23:56 ` NeilBrown
2011-10-23 9:03 ` Alexander Lyakas
2011-10-23 22:55 ` NeilBrown
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