Multiple client session considerations

This topic lists some items to consider when working with multiple client sessions.

The following factors can affect the throughput of multiple sessions:

• The ability of the server to handle multiple client sessions. Is there sufficient memory, multiple storage volumes, and processor cycles to increase backup throughput?
• The ability of the client to drive multiple sessions (sufficient processor cycles, memory, etc.).
• The configuration of the client storage subsystem. File systems that are striped across multiple disks, using either software striping or RAID-5 can better handle an increase in random read requests than a single drive file system. Additionally, a single drive file system might not see performance improvement if it attempts to handle many random concurrent read requests.
• Sufficient bandwidth in the network to support the increased traffic.

Potentially undesirable aspects of running multiple sessions include:

• The client could produce multiple accounting records.
• The server might not start enough concurrent sessions. To avoid this, the server maxsessions parameter must be reviewed and possibly changed.
• A query node command might not summarize client activity.
• It is possible that files are restored instead of hard links.
  Restoring files instead of hard links can occur when the following criteria are all true:

  • You restore an entire file system.
  • During the restore operation, the value of the resourceutilization option is greater than 1.
  • The file system contained hard links when the file system was backed up.

  The chance of restoring linked files instead of hard links increases as the number of sessions increases. When you restore a file system that contained hard links when the file system was backed up, set resourceutilization=1 to ensure that hard links are restored.