Fwd: Re: file write that exceeds thin device capacity
by Todd Gill
FYI
-------- Forwarded Message --------
Subject: Re: file write that exceeds thin device capacity
Date: Wed, 14 Nov 2018 09:10:04 +1100
From: Dave Chinner <david(a)fromorbit.com>
To: Todd Gill <tgill(a)redhat.com>
CC: linux-xfs(a)vger.kernel.org
On Tue, Nov 13, 2018 at 02:57:18PM -0500, Todd Gill wrote:
> Hi,
>
> This script creates a 1 TB thin device (device mapper) backed by 1 GB
> of physical space. The script then writes more than 1 GB via
> $BLOCK_SIZE files to XFS. I'm testing to see if recovery can be
> automated.
>
> https://paste.fedoraproject.org/paste/ropelNyOQWCjk3hfK0jltA
>
> When the $BLOCK_SIZE passed to dd is 4k - dd gets an error on the file
> write that exceeds the physical capacity that backs the thin device.
> XFS doesn't indicate any problems.
user data write error.
> If I set the $BLOCK_SIZE to 32k - I see entries in the system log that
> indicate XFS loops retrying the writes.
>
> Is that expected? Is it just more likely to happen with larger block
> sizes?
>
> I’m looking to understand how to recover when a thin device runs out of
> space under XFS.
>
> Example system log entries:
>
> [ +5.048997] XFS (dm-3): metadata I/O error: block 0xf0000
> ("xfs_buf_iodone_callback_error") error 28 numblks 32
> [ +1.376913] XFS: Failing async write: 1164 callbacks suppressed
> [ +0.000004] XFS (dm-3): Failing async write on buffer block 0xf0020.
> Retrying async write.
Filesystem Metadata write error. XFS is configured to retry them by
default. Failing this write will shut down the filesystem as it is a
corruption vector.
If you expand your thin device at this point, the
write will then succeed and the filesystem will continue to operate
normally.
If you configure your filesystem (through
/sys/fs/xfs/<dev>/error/...) to fail metadata writes on ENOSPC
errors, then it will shutdown the filesystem rather than wait for
the thinp device to be expanded.
Cheers,
Dave.
--
Dave Chinner
david(a)fromorbit.com
4 years, 10 months
Is stratis user ready?
by Eduardo Minguez
Hi all,
With the recent 1.0.1 release, I've try to look for some documentation on
how to use stratis as user* but I couldn't find anything in the website so
I'm wondering if it is user ready yet or if there is some documentation on
how to use it that I miss.
Thanks!!!
* Step by step tutorial on how to install it, basic commands, etc.
--
Eduardo Mínguez Pérez
Senior System Engineer, RHCE, RHCSA
Red Hat Spain
✉ edu(a)redhat.com
4 years, 10 months