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From: Martin <m_btrfs@ml1.co.uk>
To: linux-btrfs@vger.kernel.org
Subject: Re: What to do about snapshot-aware defrag
Date: Wed, 04 Jun 2014 14:15:01 +0100	[thread overview]
Message-ID: <lmn64l$s0g$1@ger.gmane.org> (raw)
In-Reply-To: <m49fvjlghh2.fsf@coffee.modeemi.fi>

On 04/06/14 10:19, Erkki Seppala wrote:
> Martin <m_btrfs@ml1.co.uk> writes:
> 
>> The *ONLY* application that I know of that uses atime is Mutt and then
>> *only* for mbox files!...
> 
> However, users, such as myself :), can be interested in when a certain
> file has been last accessed. With snapshots I can even get an idea of
> all the times the file has been accessed.
> 
>> *And go KISS and move on faster* better?
> 
> Well, it in uncertain to me if it truly is better that btrfs would after
> that point no longer truly even support atime, if using it results in
> blowing up snapshot sizes. They might at that point even consider just
> using LVM2 snapshots (shudder) ;).

Not quite... My emphasis is:


1:

Go KISS for the defrag and accept that any atime use will render the
defrag ineffective. Give a note that the noatime mount option should be
used.


2:

Consider using noatime as a /default/ being as there are no known
'must-use' use cases. Those users still wanting atime can add that as a
mount option with the note that atime use reduces the snapshot defrag
effectiveness.


(The "for/against atime" is a good subject for another thread!)


Go fast KISS!

Regards,
Martin




  reply	other threads:[~2014-06-04 13:15 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-30 20:43 What to do about snapshot-aware defrag Josef Bacik
2014-05-30 22:00 ` Martin
2014-05-31 23:51   ` Brendan Hide
2014-06-01  1:52     ` Duncan
2014-06-02  3:07     ` Mitch Harder
2014-06-02 13:19       ` Josef Bacik
2014-06-02 13:22   ` Josef Bacik
2014-06-03 23:54     ` Martin
2014-06-04  9:19       ` Erkki Seppala
2014-06-04 13:15         ` Martin [this message]
2014-06-04 19:33           ` Chris Murphy

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