softwareUpdate-256I recently had the opportunity to upgrade a BIG-IP 6400 unit from TMOS version 9.4.4 to TMOS version 9.4.8.  Everything went very well with the upgrade, but I did run into two little snags that I wanted to mention.  I will cover the main issue first and then write up another story in a day or two about the other.

The unit that was upgraded has three modules running on it, the GTM, LTM and WA modules.  The issue is caused by the WebAccelerator module logging to many messages out to the PVAC log, which can lead to excessive disk I/O and may cause the log file to grow so large it crashes the WebAccelerator module.  It is now a Known Issue and is being tracked in CR127854.  So if you have upgraded to TMOS 9.4.8 and you are running the WebAcceleration module you might want to keep an eye out for this!

If you believe you have a unit experiencing this issue I would advise you to contact F5 Technical Support and open a case with them.  An Engineering Hotfix can be provided to you that addresses this issue.  In the meantime, if you are able to stop using the WebAccelerator class profiles, then I would suggest not using those until you have downloaded and applied the hotfix.  Below is the text from AskF5.com regarding the issue.

Known Issue
Updated: 9/17/09 10:11 AM
Known Issue

When an object is proxied by PVAC on BIG-IP WebAccelerator version 9.4.8, several debug messages are logged to the /var/log/wa/pvac.log file.

The messages for an image object appear similar to the following example:

WA Debug: appId = 0x36d3
WA Debug: appConfigId = 0x36d4
WA Debug: appSignId = 0x0
WA Debug: AppId [0xab0a] temp [0x0][0x0][0xab][0xa]

The messages for an HTML object appear similar to the following example:

WA Debug: appId = 0x36d3
WA Debug: appConfigId = 0x36d4
WA Debug: appSignId = 0x0
WA Debug: AppId [0xab3f] temp [0x0][0x0][0xab][0x3f]
WA Debug: Preventing IBR for: App: [14036:Site.Application Generated.Pages] PolicyNode: [43839] maxAge: [0]

The debug messages reflect normal system operation, and may be safely ignored. However, as a result of logging these messages, you may observe the following side effects:

  • Excessive disk I/O required to log the messages may negatively impact system performance
  • The PVAC log file may grow to an excessive size, causing the BIG-IP WebAccelerator module to become unstable and crash

F5 Networks Product Development is tracking this issue as CR127854.

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