Jetstress: Unevenly distributing users across storage groups.


Question:


I have uneven distribution of users across storage groups. Storage group 1 has 700 GB with 739 users and storage group 2 has 350 GB with 261 users.


Can I run multiple instances of JetstressWin.exe or JetstressCmd.exe (one instance per storage group) for database files of different sizes that I have manually prepared?


Answer:


I should discourage running multiple instances of Jetstress — that can possibly lead to conflicting database performance counter names. I should encourage even distribution of load generation across storage groups.


Jetstress makes even load distribution by default. But, Jetstress accommodates the case where a user can set in the configuration file to use different numbers of IOPS for each storage group.


The following configuration has two things to note:


·         Each storage group has four database files on J:\ and 2 database files on K:\ — every database file has the same size when they are prepared.


·         Each storage group has IOPS bias numbers — each database transactions randomly picks a database instance (also called a storage group) based on IOPS bias. The distribution will be like 73.9% of transactions on storage group 1 and 26.1% of transactions on storage group 2.


<StorageGroups>


  <StorageGroup IopsBias=739>


      <DatabasePaths>


        <Path>J:\</Path>


        <Path>J:\</Path>


        <Path>J:\</Path>


        <Path>J:\</Path>


      </DatabasePaths>


      <LogPath>E:\</LogPath>


  </StorageGroup>


  <StorageGroup IopsBias=261>


      <DatabasePaths>


        <Path>K:\</Path>


        <Path>K:\</Path>


      </DatabasePaths>


      <LogPath>F:\</LogPath>


  </StorageGroup>


</StorageGroups>


Jetstress logs batch transactions stats at the end of a test as follows.


The following log text shows that Jetstress has run 132505 and 46791 batch transactions (74% and 26%) on storage group 1 and 2.


3/16/2007 12:39:43 PM — JetInterop batch transaction stats: 132505, and 46791.


This posting is provided “AS IS” with no warranties, and confers no rights.

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