[systemd-devel] R: Re: Slow startup of systemd-journal on BTRFS

[Goffredo Baroncelli <kreijack@libero.it>]

>----Messaggio originale----
>Da: lists at colorremedies.com
>Data: 12/06/2014 2.40
>A: <kreijack at inwind.it>, "Goffredo Baroncelli"<kreijack at libero.it>
>Cc: "systemd Mailing List"<systemd-devel at lists.freedesktop.org>, "linux-btrfs"
<linux-btrfs at vger.kernel.org>
>Ogg: Re: Slow startup of systemd-journal on BTRFS
>
>
>On Jun 11, 2014, at 3:28 PM, Goffredo Baroncelli <kreijack at libero.it> wrote:
>> 
>> If someone is able to suggest me how FRAGMENT the log file, I can try to 
collect more scientific data.
>
>So long as you're not using compression, filefrag will show you fragments of 
systemd-journald journals. I can vouch for the behavior 
> you experience without xattr +C or autodefrag, but further it also causes 
much slowness when reading journal contents. LIke if I want to 
> search all boots for a particular error message to see how far back it 
started, this takes quite a bit longer than on other file systems. 
> So far I'm not experiencing this problem with autodefrag or any other 
negative side effects, but my understanding is this code is still in flux.
>
>Since the journals have their own checksumming I'm not overly concerned about 
setting xattr +C.

This is true; but it can be a general solution: the checksum of the data are 
needed during a 
scrub and/or a RAID rebuilding.

I want to investigate doing an explicit defrag once a week.


>
>Chris Murphy
G.Baroncelli