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From: Christoph Hellwig <hch@infradead.org>
To: Arkadiusz Miskiewicz <arekm@maven.pl>
Cc: xfs@oss.sgi.com
Subject: Re: Delaylog
Date: Tue, 14 Sep 2010 19:23:21 -0400	[thread overview]
Message-ID: <20100914232321.GA11123@infradead.org> (raw)
In-Reply-To: <201009142106.24448.arekm@maven.pl>

On Tue, Sep 14, 2010 at 09:06:24PM +0200, Arkadiusz Miskiewicz wrote:
> On Tuesday 14 of September 2010, Fabricio Archanjo wrote:
> > Hey all,
> > 
> >    I just trying delaylog in my server that has a mysql database. When
> > i monted my /var/lib/mysql with delaylog option, it showed me:
> > "Enabling EXPERIMENTAL delayed logging feature - use at your own
> > risk". Ok, i know it's experimental, but what kind of problem could i
> > have using delaylog?

Basically you could hit a race or lockup in the code under high stress
or unusual workloads.  So far we just had one possible lockup under very
high dbench load.

> ... and what problems in case of system hang or power loss when compared to 
> nodelaylog mode?

The same as with the old log code - if you crash recently written data
might be lost.  Unless a really severe bugs shows up (in either the old
or new code) that only includes data since the last fsync/sync.  The
quantitative difference is that a lot more metadata is now cached in
core, so on a crash you can lose more recently written but not synced
metadata.

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      parent reply	other threads:[~2010-09-14 23:22 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <AANLkTin6FSBK3tMXhSxDuLdjyb+R0LhNnaa2CKt37FcV@mail.gmail.com>
2010-09-14 19:06 ` Delaylog Arkadiusz Miskiewicz
2010-09-14 19:20   ` Delaylog Fabricio Archanjo
2010-09-14 20:03   ` Delaylog Stan Hoeppner
2010-09-14 21:32     ` Delaylog Fabricio Archanjo
2010-09-14 23:23   ` Christoph Hellwig [this message]

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