From: Duncan <1i5t5.duncan@cox.net>
To: linux-btrfs@vger.kernel.org
Subject: Re: Unable to rebuild a 3 drive raid1 - blocked for more than 120 seconds.
Date: Thu, 1 May 2014 06:01:34 +0000 (UTC) [thread overview]
Message-ID: <pan$30fe3$a9a78108$41476c4c$c7949e11@cox.net> (raw)
In-Reply-To: CAE6A3M0zmzDmLKzRDALNeLsqx72ttC8CA74-GfuSXN1TwJW-0A@mail.gmail.com
Saran Neti posted on Thu, 01 May 2014 00:48:22 -0400 as excerpted:
> I had 3 x 3 TB drives [...] Then one of the drives got busted.
> Mounting the fs in degraded mode and adding a new fresh drive to
> rebuild raid1, generated several "...blocked
> for more than 120 seconds." messages.
> Described in
> https://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg30017.html
> are two possible causes, fragmentation due to COW and hardlinks, both of
> which I think are unlikely in this case. I can mount in degraded mode
> and read files, but that's about it. Is there something I'm missing? Any
> debugging tips would be appreciated.
Just a btrfs user and list regular here, not a dev, but...
You're to be commended for all that useful information you posted. Way
more helpful than most manage in their first round. =:^) But it's enough
to see I can't be of much help but for the below, so it's mostly snipped
here as unnecessary for this reply...
I've several times seen the devs request a magic-sysrq-w dump for cases
like this. That should be alt-srq-w on x86 hardware, or
echo w > /proc/sysrq-trigger (should work in a VM also).
That dumps IO-blocked tasks, letting the devs see where things are
screwing up.
(If magic-srq is new to you, there's more about it in
$KERNDIR/Documentation/sysrq.txt. Last I looked a google returned some
pretty good hits discussing it, too.)
--
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman
next prev parent reply other threads:[~2014-05-01 6:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-01 4:48 Unable to rebuild a 3 drive raid1 - blocked for more than 120 seconds Saran Neti
2014-05-01 6:01 ` Duncan [this message]
2014-05-02 1:58 ` Chris Murphy
2014-05-02 2:23 ` Chris Murphy
2014-05-02 4:13 ` Chris Murphy
2014-05-02 2:16 ` Anand Jain
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