Sessions waiting for archive to disk

If the Canister Status report indicates that there are a high number of Sessions waiting for archive to disk, then the Short Term Canister is unable to write to the Long Term Canister at a sufficient rate.

In most cases, this issue is caused by a basic I/O throughput problem. The incoming session count is higher than the outgoing session count. You can verify this issue through the DecoupleEx status report.

To fix this issue, you should identify if there is excess I/O capacity available using a tool such as SQLIO while Discover is running.

  • If there is excess capacity, you can experiment with increasing the number of Session Processors, whose primary function is to compress sessions for storage on disk. By increasing the processing units, more sessions can be written to disk at a faster rate. After raising this number, you may notice that the rate at which sessions are processed is increasing. For more information, see the Session Processors value in the "Configuring the Canister" in the Unica Discover Configuration Manual.
  • If there is no excess capacity, there is no software solution for this issue. Please review your storage configuration and capacity.