From: Rich Johnston <rjohnston@sgi.com>
Subject: Re: [PATCH 10/10] xfstests: add disk failure simulation test
Date: Fri, 1 Mar 2013 14:11:15 -0600
Message-ID: <51310B63.4070105@sgi.com>
References: <1361356935-29153-1-git-send-email-dmonakhov@openvz.org>
	<1361356935-29153-11-git-send-email-dmonakhov@openvz.org>
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Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
	dchinner@redhat.com, xfs@oss.sgi.com
To: Dmitry Monakhov <dmonakhov@openvz.org>
In-Reply-To: <1361356935-29153-11-git-send-email-dmonakhov@openvz.org>
Errors-To: xfs-bounces@oss.sgi.com
Sender: xfs-bounces@oss.sgi.com

On 02/20/2013 04:42 AM, Dmitry Monakhov wrote:
> There are many situations where disk may fail for example
> 1) brutal usb dongle unplug
> 2) iscsi (or any other netbdev) failure due to network issues
> In this situation filesystem which use this blockdevice is
> expected to fail(force RO remount, abort, etc) but whole system
> should still be operational. In other words:
> 1) Kernel should not panic
> 2) Memory should not leak
> 3) Data integrity operations (sync,fsync,fdatasync, directio) should fail
>     for affected filesystem
> 4) It should be possible to umount broken filesystem
>
> Later when disk becomes available again we expect(only for journaled filesystems):
> 5) It will be possible to mount filesystem w/o explicit fsck (in order to caught

typo                                     s/caught/catch/g

>     issues like https://patchwork.kernel.org/patch/1983981/)
> 6) Filesystem should be operational
> 7) After mount/umount has being done all errors should be fixed so fsck should
>     not spot any issues.
>
> This test use fault enjection (CONFIG_FAIL_MAKE_REQUEST=y config option )
   May want to mention all the kernel config options required.
i.e. CONFIG_FAULT_INJECTION=y ... are there others?
CONFIG_FAULT_INJECTION_DEBUG_FS=y ???

> which force all new IO requests to fail for a given device. Xfs already has
   to force

> XFS_IOC_GOINGDOWN ioctl which provides similar behaviour, but it is fs speciffic

typos s/behaviour/behavior/g  s/speciffic/specific
                                         > and it does it in an easy way 
because it perform freeze_bdev() before actual
> shotdown.
typo s/shotdown/shutdown/g

>
> Test run fsstress in background and then force disk failure.
> Once disk failed it check that (1)-(4) is true.
   Once the disk fails, check that (1)-(4) are true.

> Then makes disk available again and check that (5)-(7) is also true
        make the disk ...                                 are
>
> BE CAREFUL!! test known to cause memory corruption for XFS
> see: https://gist.github.com/dmonakhov/4953045
>


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