[systemd-devel] Slow startup of systemd-journal on BTRFS

Kai Krakow hurikhan77 at gmail.com
Sat Jun 14 13:13:15 PDT 2014


Goffredo Baroncelli <kreijack at libero.it> schrieb:

> I am looking at the source, and yes, it does. To be honest it seems to
> defragment only on btrfs.

Oh that seems true... Then defragmenting and relocating is probably a todo 
item. I'm sure I've read about it somewhere.

>> If it
>> does, the question is: where to relocate in a multi devices file system?
> 
> Systemd uses the defrag capability of btrfs.

man:systemd-readahead says it relocates and defrags if supported. Scanning 
through the source, it only defrags.

>> That means, you have to enable systemd-readahead-collect, tho.
> I have to admit that I disabled it. I will make some test also with
> readhead enabled.

Take care to enable all needed services to enable defrag... If your services 
make use of journal file loading these files should also become part of the 
process. You can check with "/usr/lib/systemd/systemd-readahead analyze". 
The state is stored in /.readahead.

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