Re: Lots of harddrive chatter on after booting with btrfs on root (slow boot)

[Gabriel de Perthuis <g2p.code@gmail.com>]

On Sat, 20 Jul 2013 17:15:50 +0200, Jason Russell wrote:
> Ive also noted that this excessive hdd chatter does not occur
> immediately after a fresh format with arch on btrfs root.
> 
> Ive made some deductions/assumptions:
> This only seems to occur with btrfs roots.
> This only happens after some number of reboots OR after the partition
> fills up a little bit.
> Im pretty sure of ruled out everything except for the filesystem.

In my experience (as of 3.8 or so), Btrfs performance degrades on a
filled-up filesystem, even a comparatively new one.  Various
background workers start to eat io according to atop.

> I have just done two clean installs to more thoroughly compare ext4
> and btrfs roots. So far no excessive hdd chatter from btrfs.
> 
> I have also seen what I have described on two other computers
> (different hardware entirely) where there is lots of hdd chatter from
> btrfs root, and nothing from ext4.
> 
> Here are two threads:
> https://bbs.archlinux.org/viewtopic.php?pid=1117932
> https://bbs.archlinux.org/viewtopic.php?pid=1301684