Re: price to pay for nocow file bit?

[Koen Kooi <koen@dominion.thruhere.net>]

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Chris Murphy schreef op 08-01-15 om 09:24:
> On Wed, Jan 7, 2015 at 1:10 PM, Josef Bacik <jbacik@fb.com> wrote:
>> On 01/07/2015 12:43 PM, Lennart Poettering wrote:
>>> 
>>> Heya!
>>> 
>>> Currently, systemd-journald's disk access patterns (appending to the 
>>> end of files, then updating a few pointers in the front) result in 
>>> awfully fragmented journal files on btrfs, which has a pretty 
>>> negative effect on performance when accessing them.
>>> 
>> 
>> I've been wondering if mount -o autodefrag would deal with this problem
>> but I haven't had the chance to look into it.
> 
> I've been using autodefrag and haven't run into journal corruptions that
> I can attribute to btrfs since the last one was fixed over a year ago.
> Chris Mason has suggested preference to use of autodefrag for this use
> case rather than xattr +C. But I don't know the time frame for autodefrag
> by default, it's come up a couple times but it's not the default yet.

Same here, no issues with using autodefrag and journals.

regards,

Koen

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