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From: Josef Bacik <jbacik@fb.com>
To: Kent Overstreet <kent.overstreet@gmail.com>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"david@fromorbit.com" <david@fromorbit.com>,
	"hch@lst.de" <hch@lst.de>
Subject: Re: Simulating disk failure with a writeback cache
Date: Tue, 20 Dec 2016 01:01:29 +0000	[thread overview]
Message-ID: <3A97B8BF-B65F-4A7D-878F-82D73327B3A9@fb.com> (raw)
In-Reply-To: <20161219215306.vmkhgwifrj5ph2qr@moria.home.lan>


> On Dec 19, 2016, at 4:53 PM, Kent Overstreet <kent.overstreet@gmail.com> wrote:
> 
>> On Mon, Dec 19, 2016 at 04:00:40PM -0500, Josef Bacik wrote:
>> Ok that works fine in the short term for you, but ideally you wouldn't have
>> to fix the test every time you wanted to run it on bcachefs.  Do you have a
>> suggestion of how to make this generic enough to support you as well without
>> dd'ing the whole drive?  Thanks,
> 
> Yes, but it'd be a lot of work :)
> 
> Change log-writes so that instead of replaying the log, you have it create a
> block device representing that specific point in the log - and then service read
> requests by looking them up however you like. So, it'd be just like mounting
> snapshots.
> 
> It might not be too difficult since we can deal with crappy performance or
> memory usage here, but I don't know if it's really worth the effort. 

One thing I was definitely going to do is use the dm thin provisioning so I could snapshot between each check so we don't have to replay from the beginning every time we want to check a different mark.  Replaying the whole thing is fine for small runs like the fsx thing, but when you want to say run fsstress for a minute and replay to every fua and fsck and mount it gets tedious fast.  Thanks,

Josef

  reply	other threads:[~2016-12-20  1:01 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-15  2:26 Simulating disk failure with a writeback cache Kent Overstreet
2016-12-15  4:15 ` Josef Bacik
2016-12-18 20:12   ` Kent Overstreet
2016-12-18 20:38     ` Josef Bacik
2016-12-18 20:46       ` Kent Overstreet
2016-12-18 21:19         ` Josef Bacik
2016-12-19  2:51           ` Kent Overstreet
2016-12-19  3:07             ` Kent Overstreet
2016-12-19 12:58               ` Josef Bacik
2016-12-19 15:27               ` Josef Bacik
2016-12-19 20:55                 ` Kent Overstreet
2016-12-19 21:00                   ` Josef Bacik
2016-12-19 21:53                     ` Kent Overstreet
2016-12-20  1:01                       ` Josef Bacik [this message]
2016-12-20  1:30                         ` Kent Overstreet

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