[Dovecot] Dovecot performance on GFS clustered filesystem

[Diego Liziero]

On Wed, Sep 24, 2008 at 9:18 PM, Diego Liziero <diegoliz at gmail.com> wrote:
> I've read somewhere that one of gfs2 goals was to improve performance
> for directory access with many files.
>
> I've tested it doing a simple ls in a directory with many test empty
> files in gfs and it was _really_ slow, doing the ls on a gfs2 with the
> same amount of emtpy files is actually faster.
>
> But when I tested gfs2 with bonnie++ I got fewer sequential I/O speed
> than in gfs (consider that I tested a beta version of gfs2 some months
> ago, maybe things are better now).

This seems true only for sequential write speed.

> So my conclusion of the tests was that gfs is best with mbox, gfs2
> beta with maildir.
>
> But, again, I haven't tested gfs2 improvements recently.
>
> Regards,
> Diego.

I lauched bonnie++ on the same lvm2 partition formatted with different
filesystems to test their speed.
Consider that I launced the test just one time per filesystem, so the
numbers should not be considered sharp, but with a certain percentage
of error.

With clustered filesystems (gfs and gfs2) the test has been launched
on the same box, but with the fillesystem mounted on two nodes.
Option used to format gfs and gfs2: "-r 2048 -p lock_dlm  -j 4"

The test box has two dual-core Opteron processors, 8 Gb of ram, two
4Gb fiber channel HBA, gigabit ethernet (for the distributed lock
manager connection) and Centos 5.2 x86_64 installed.

With this configuration it seems that:
gfs is faster than gfs2 when writing sequential blocks, much faster in
creating and deleting files;
gfs2 seems to have a faster read speed.

Regards,
Diego.
----
bonnie++ -s 16g
Version 1.03c       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Filesystem     Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
ext2            16G 69230  95 149430  47 54849  25 71681  90 215568
54 473.3   1
xfs             16G 62828  94 135482  54 64010  28 71841  92 238351
51 632.3   2
ext3            16G 56485  93 115398  68 56051  32 73536  92 211219
48 552.0   2
gfs             16G 47079  98 124123  82 42651  53 65692  91 189533
65 431.5   3
gfs2            16G 40203  77  74620  53 52596  39 73187  93 226909
58 496.2   2

                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
ext2             16  3810  99 +++++ +++ +++++ +++  2395  99 +++++ +++ 10099  99
xfs              16  2446  51 +++++ +++  1073  24  2019  59 +++++ +++   796  21
ext3             16  5597  77 +++++ +++ 16764  99 19450  99 +++++ +++ +++++ +++
gfs              16   882  40 +++++ +++  4408  82  1001  56 +++++ +++  2734  69
gfs2             16   457   0 +++++ +++   994   0   477   0 +++++ +++   995  29