Re: Benchmark: Dell/Perc 6, 8 disk RAID 10

Craig James <craig_james@xxxxxxxxxxxxxx> · Thu, 13 Mar 2008 07:36:47 -0700

Doug Knight wrote:
All,
I am in the process of specing out a purchase for our production 
systems, and am looking at the Dell 2950s as well. I am very interested 
to see where this thread goes, and what combinations work with different 
application loading types. Our systems will have one pair of 
heartbeat-controlled, drbd mirrored servers running postgresql 8.3, with 
a more write intensive, multiple writers and few readers application. 
The other similarly configured pair will have lots of readers and few 
writers. Our initial plan is RAID 10 for the database (four 300GB 15K 
drives in an attached MD1000 box) and RAID 1 for the OS (pair of 73GB 
drives internal to the 2950). PERC 6i for the internal drives (256MB 
battery backed cache), PERC 6E for the external drives (512MB battery 
backed cache). 8GB RAM, also dual Gig NICs for internet and 
heartbeat/drbd. Not sure which processor we're going with, or if 8GB 
memory will be enough. Keep the benchmarks coming.

We considered this configuration too.  But in the end, we decided that by going with the 146 GB 2.5" drives, we could get 8 disks in the main box, and save the cost of the MD1000, which almost doubles the price of the system.  We end up with a 546 GB RAID assembly, more than enough for our needs.

I think that 8 10K disks in a RAID 10 will be faster than 4 15K disks, and you only gain a little space (two 300GB versus four 146GB).  So it seemed like we'd be paying more and getting less.  With the battery-backed Perc 6i RAID, the advice seemed to be that the OS, WAL and Database could all share the disk without conflict, and I think the numbers will back that up.  We're not in production yet, so only time will tell.

Craig

Doug

On Thu, 2008-03-13 at 04:11 -0400, Justin Graf wrote:
I recent just got a new server also from dell 2 weeks ago
went with more memory slower CPU, and smaller harddrives
 have not run pgbench

Dell PE 2950 III
2 Quad Core 1.866 Ghz
16 gigs of ram.
8 hard drives 73Gig 10k RPM SAS
2 drives in Mirrored for OS, Binaries, and WAL
6 in a raid 10
Dual Gig Ethernet
OS Ubuntu 7.10
-----------------------------------------------

Version 1.03
                     ------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
PriData 70000M  51030   90   107488    29      50666 10     38464 
65     102931     9    268.2 0

------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
PriData,70000M,51030,90,107488,29,50666,10,38464,65,102931,9,268.2,0,16,
+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++

the difference in our results are interesting.

What are the setting on the RAID card .  I have the cache turned on 
with Read Ahead 

---- Message from Craig James <craig_james@xxxxxxxxxxxxxx> 
<mailto:craig_james@xxxxxxxxxxxxxx> at 03-12-2008 09:55:18 PM ------

    I just received a new server and thought benchmarks would be
    interesting.  I think this looks pretty good, but maybe there are
    some suggestions about the configuration file.  This is a web app,
    a mix of read/write, where writes tend to be "insert into ...
    (select ...)" where the resulting insert is on the order of 100 to
    10K rows of two integers.  An external process also uses a LOT of
    CPU power along with each query.

    Thanks,
    Craig

    Configuration:
      Dell 2950
      8 CPU (Intel 2GHz Xeon)
      8 GB memory
      Dell Perc 6i with battery-backed cache
      RAID 10 of 8x 146GB SAS 10K 2.5" disks

    Everything (OS, WAL and databases) are on the one RAID array.

    Diffs from original configuration:

    max_connections = 1000
    shared_buffers = 400MB
    work_mem = 256MB
    max_fsm_pages = 1000000
    max_fsm_relations = 5000
    wal_buffers = 256kB
    effective_cache_size = 4GB

    Bonnie output (slightly reformatted)

    ------------------------------------------------------------------------------

    Delete files in random order...done.
    Version  1.03
             ------Sequential Output------       --Sequential Input-
         --Random-
          -Per Chr-   --Block--    -Rewrite-     -Per Chr-   --Block--
       --Seeks--
     Size K/sec %CP   K/sec  %CP   K/sec  %CP    K/sec %CP   K/sec
     %CP    /sec %CP
      16G 64205  99   234252  38   112924  26    65275  98   293852
     24   940.3   1

             ------Sequential Create------    --------Random
    Create--------
          -Create--   --Read---   -Delete--   -Create--   --Read---
      -Delete--
    files  /sec %CP    /sec %CP    /sec %CP    /sec %CP    /sec %CP
       /sec %CP
       16 12203  95   +++++ +++   19469  94   12297  95   +++++ +++
      15578  82

    www.xxx.com,16G,64205,99,234252,38,112924,26,65275,98,293852,24,940.3,1,16,12203,95,+++++,+++,19469,94,12297,95,+++++,+++,15578,82

    ------------------------------------------------------------------------------

    $ pgbench -c 10 -t 10000 -v test -U test
    starting vacuum...end.
    starting vacuum accounts...end.
    transaction type: TPC-B (sort of)
    scaling factor: 1
    number of clients: 10
    number of transactions per client: 10000
    number of transactions actually processed: 100000/100000
    tps = 2786.377933 (including connections establishing)
    tps = 2787.888209 (excluding connections establishing)

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