Re: raid array seek performance

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On Tue, Sep 13, 2011 at 12:13 PM, Samuel Gendler <sgendler@xxxxxxxxxxxxxxxx> wrote:
I'm just beginning the process of benchmarking and tuning a new server.  Something I really haven't done before.  I'm using Greg's book as a guide.  I started with bonnie++ (1.96) and immediately got anomalous results (I think).

Hardware is as follows:

2x quad core xeon 5504 2.0Ghz, 2x4MB cache
192GB DDR3 1066 RAM
24x600GB 15K rpm SAS drives
adaptec 52445 controller

The default config, being tested at the moment, has 2 volumes, one 100GB and one 3.2TB, both are built from a stripe across all 24 disks, rather than splitting some spindles out for one volume and another set for the other volume.  At the moment, I'm only testing against the single 3.2TB volume.

The smaller volume is partitioned into /boot (ext2 and tiny) and / (ext4 and 91GB).  The larger volume is mounted as xfs with the following options (cribbed from an email to the list earlier this week, I think): logbufs=8,noatime,nodiratime,nobarrier,inode64,allocsize=16m

Bonnie++ delivered the expected huge throughput for sequential read and write.  It seems in line with other benchmarks I found online.  However, we are only seeing 180 seeks/sec, but seems quite low.  I'm hoping someone might be able to confirm that and. hopefully, make some suggestions for tracking down the problem if there is one.

Results are as follows:

1.96,1.96,newbox,1,1315935572,379G,,1561,99,552277,46,363872,34,3005,90,981924,49,179.1,56,16,,,,,19107,69,+++++,+++,20006,69,19571,72,+++++,+++,20336,63,7111us,10666ms,14067ms,65528us,592ms,170ms,949us,107us,160us,383us,31us,130us


Version      1.96   ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
newzonedb.z1.p 379G  1561  99 552277  46 363872  34  3005  90 981924  49 179.1  56
Latency              7111us   10666ms   14067ms   65528us     592ms     170ms
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files:max:min        /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
newbox            16 19107  69 +++++ +++ 20006  69 19571  72 +++++ +++ 20336  63
Latency               949us     107us     160us     383us      31us     130us


My seek times increase when I reduce the size of the file, which isn't surprising, since once everything fits into cache, seeks aren't dependent on mechanical movement.  However, I am seeing lots of bonnie++ results in google which appear to be for a file size that is 2x RAM which show numbers closer to 1000 seeks/sec (compared to my 180).  Usually, I am seeing 16GB file for 8GB hosts.  So what is an acceptable random seeks/sec number for a file that is 2x memory?  And does file size make a difference independent of available RAM such that the enormous 379GB file that is created on my host is skewing the results to the low end?



[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux