Jetstress: Unevenly distributing users across storage groups.

  • Article

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.