Skip site navigation (1)Skip section navigation (2)
Date:      Tue, 17 Jan 2017 12:32:28 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-bugs@FreeBSD.org
Subject:   [Bug 216178] ZFS ARC and L2ARC are unrealistically large, maybe after r307265
Message-ID:  <bug-216178-8@https.bugs.freebsd.org/bugzilla/>

next in thread | raw e-mail | index | archive | help
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D216178

            Bug ID: 216178
           Summary: ZFS ARC and L2ARC are unrealistically large, maybe
                    after r307265
           Product: Base System
           Version: 11.0-STABLE
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: freebsd-bugs@FreeBSD.org
          Reporter: lev@FreeBSD.org

I have two ZFS pools: one with single device (zroot) and one raidz with 5
devices (zstor). zstor has L2ARC of 185GB.

% zpool list -v
NAME          SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH=20
ALTROOT
zroot        39.9G  13.7G  26.2G         -    50%    34%  1.00x  ONLINE  -
  gpt/root   39.9G  13.7G  26.2G         -    50%    34%
zstor        13.6T  8.55T  5.08T         -    22%    62%  1.00x  ONLINE  -
  raidz1     13.6T  8.55T  5.08T         -    22%    62%
    ada1         -      -      -         -      -      -
    ada2         -      -      -         -      -      -
    ada3         -      -      -         -      -      -
    ada4         -      -      -         -      -      -
    ada5         -      -      -         -      -      -
cache            -      -      -         -      -      -
  gpt/l2arc   185G   185G   148M         -     0%    99%
%

Both pools has compression enabled (lz4), but compression ratio on zstor is
negligible (it contains mostly media files, like music, films and RAW digit=
al
photos). zroot has compression rate about 1.4:

% zfs get compressratio zroot zstor
NAME   PROPERTY       VALUE  SOURCE
zroot  compressratio  1.43x  -
zstor  compressratio  1.00x  -
%

My system has 16GB of physical memory.

After upgrade to post-r307266 system (10-STABLE) different system tools sta=
rts
to show unrealistically large ARC. Upgrade to 11-STABLE (after r307265) doe=
n't
help either. It looks like this:

(1) top output:
Mem: 195M Active, 4678M Inact, 9656M Wired, 1373M Free
ARC: 75G Total, 247M MFU, 6135M MRU, 1190K Anon, 77M Header, 556M Other
Swap: 8192M Total, 8192M Free

(2) zfs-stats -A output:
ARC Size:                               515.61% 74.92   GiB
        Target Size: (Adaptive)         100.00% 14.53   GiB
        Min Size (Hard Limit):          12.50%  1.82    GiB
        Max Size (High Water):          8:1     14.53   GiB


This starts after some uptime with disc activity (like buildworld & backup)=
 and
could be reset to "normal" state with reboot only.

Sometimes, L2ARC starts to grow up to 400% of its size, too. L2ARC shows a =
lot
of checksum errors as it grow larger than physical size.

--=20
You are receiving this mail because:
You are the assignee for the bug.=



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-216178-8>