Re: Anyone tried out btrbk yet?

From: Donald Pearson <donaldwhpearson@gmail.com>
To: Marc MERLIN <marc@merlins.org>
Cc: sander@humilis.net, Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: Anyone tried out btrbk yet?
Date: Mon, 20 Jul 2015 00:15:26 -0500	[thread overview]
Message-ID: <CAC=t97CcemZzBjABSLS5etSF6B-67SvwL25q62hxv2de3zLPbw@mail.gmail.com> (raw)
In-Reply-To: <20150715214913.GG5274@merlins.org>

I'm starting to think there's something wrong with creating and
removing snapshots that leaves btrfs-cleaner either locked up or
nearly so.  If the btrfs-cleaner process was hard-disk limited I
should be seeing some HDD I/O to coincide but I don't.

So far btrfs-cleaner is has been using lots of CPU for 1900+ hours and
my disk I/O is basically idle.  My hourly snaps via cronjob stalled 11
hours ago.

Otherwise attempts to read/write to the filesystem appear to be
perfectly normal.

[root@san01 virtual_machines]# ps aux | grep btrfs-cleaner
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root      1292     0.0      0.0      0     0     ?        S    Jul16
     0:01   [btrfs-cleaner]
root      5796     0.0      0.0      0     0     ?        S    Jul16
     0:00   [btrfs-cleaner]
root      6005     21.3    0.0      0     0     ?        S    Jul16
 943:34   [btrfs-cleaner]
root     14040    43.3    0.0      0     0     ?        R    Jul16
1916:05   [btrfs-cleaner]

[root@san01 virtual_machines]# ls -lah /run | grep backup
-rw-r--r--   1 root     root       11 Jul 20 00:00 backup.home.daily
-rw-r--r--   1 root     root       11 Jul 20 00:00 backup.root.daily
-rw-r--r--   1 root     root       11 Jul 20 00:01 backup.store.daily
-rw-r--r--   1 root     root       11 Jul 19 13:00 backup.store.hourly
-rw-r--r--   1 root     root       11 Jul 20 00:01 backup.virtual_machines.daily
-rw-r--r--   1 root     root       11 Jul 19 13:00
backup.virtual_machines.hourly
[root@san01 virtual_machines]# date
Mon Jul 20 00:14:05 CDT 2015

On Wed, Jul 15, 2015 at 4:49 PM, Marc MERLIN <marc@merlins.org> wrote:
> On Wed, Jul 15, 2015 at 01:02:29PM -0500, Donald Pearson wrote:
>> BTW, is anybody else experiencing btrfs-cleaner consuming heavy
>> resources for a very long time when snapshots are removed?
>
> Yes, that's normal. It spends a long time to reclaim blocks and free
> them, especially if they are on a hard drive and not SSD.
>
> Marc
> --
> "A mouse is a device used to point at the xterm you want to type in" - A.S.R.
> Microsoft is to operating systems ....
>                                       .... what McDonalds is to gourmet cooking
> Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901