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Thread: DB2 and SSD

  1. #1
    Join Date
    Sep 2003
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    Unanswered: DB2 and SSD

    Hi,

    Has anyone tried DB2 backed by SSD drives ? - I am getting strange results, here is what I have tested.

    I have 2 set of harware - one with HDD and the other with SSD (100%) - same amount of RAM on both, one both the servers there are 4 X 500 GB drives in RAID 5 configuration

    Both are on RHEL/DB2 10.5, created a sample database and run following script just to do some basic red/write test. This below test script takes about a minute on the server that is backed by HDD and I was expecting this to run faster on the server with SSD, but it was worst..took 4 minutes !!!

    /*******************************

    #!/bin/bash
    # script - activesim.sh
    #
    db2 connect to SAMPLE >>/dev/null
    db2 "create table xTEST like syscat.tables"
    for COUNT in {1..100}
    do
    echo $COUNT
    db2 "insert into xTEST select * from syscat.tables"
    db2 "insert into xTEST select * from xTEST"
    db2 "delete from xTEST"
    db2 "reorg table xTEST"
    done
    db2 "drop table xTEST"
    db2 "connect reset"

    *******************************/

    Any reason why server with SSD won't performance better in this case ?

    Are SSD storage not worth much for database activities, specifically when database is small and mostly all the data is in Bufferpool/memory ?

    Thanks.

  2. #2
    Join Date
    May 2012
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    May depend on the characteristics of the SSD drives - we use SSD drives only for active log drives in a mirrored pair. Are the times repeatable?
    Andy

    "All parts should go together without forcing. You must remember that the parts you are reassembling were disassembled by you. Therefore, if you can’t get them together again, there must be a reason. By all means, do not use hammer.” — IBM maintenance manual, 1975 "

  3. #3
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    Quote Originally Posted by tafster View Post
    May depend on the characteristics of the SSD drives - we use SSD drives only for active log drives in a mirrored pair. Are the times repeatable?
    You mean the elapsed times ? - yes they are repeatable, they consistently the same. And there is absolutely no other activity going on on these 2 servers.

  4. #4
    Join Date
    Nov 2011
    Posts
    334
    hi , gvphubli:
    Have you monitored the resource utilization of the two systems.
    you can use iostat -x and vmstat command to take a look into io ,memory , cpu utiliztion.
    and when the test is running , you can also get snapshot for your database.
    1.Turn on switch monitors.
    2. reset monitor all, sleep 60 s , get snapshot for database, applications.
    the following metrics should be noticed :
    pool read write time, prefetch wait time, log read write time, physical reads writes, and direct read writes.
    and please make sure the ddl of the test table are the same .

  5. #5
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    Quote Originally Posted by fengsun2 View Post
    fengsun2
    - if you look at the script its a systable, and all I am doing is bulk insert. And when you create table using LIKE option - it create a table like the referenced table with NO CONSTRAINTS...so its a very basic test via DB2/SQL

    I will certainly look at IO and Memory utilization and other perf. counter.

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