HLB - Release Notes

The data sheet for this catalog class is CatSwitchesHlb.

Version 2.0.6

This version of HLB will be available in AppLogic 1.2.4. It can also be used on AppLogic 1.2.3 and earlier 1.2.x releases.

• increased the buffer allocation for the XEN netfront driver to maximum, to handle overloads without dropping packets. NOTE: this change increases the memory requirement of HLB by 8MB. The data sheet is updated accordingly.
• corrected the worker-thread auto-allocation based on memory available (it was slightly more aggressive than necessary, allocating more than the 500 max worker threads when given max memory).
• rebuilt with the latest base appliance image (new version of the AppLogic VM agent)

Version 2.0.5

Rebuild.

Version 2.0.4

This version of HLB will be available in AppLogic 1.2.3. It can also be used on AppLogic 1.2.1 and 1.2.2.

• Fixed slow memory leak occurring when mode=synch.
• Added kernel and TCP tuning options to improve behavior under very high load.
• Rebuilt with a new version of the virtual appliance agent (vma), with fixed bug which was causing intermittent failure to report the appliance as running and aborting the application start.

Version 2.0.1

Re-built with a new base image (updated AppLogic appliance agent).

Version 1.0

Intro

This is the first release of the HTTP load balancer - HLB. It is based on the Pound load balancer program developed by Apsis GmbH (http://www.apsis.ch/pound/). The HLB appliance includes a few additions and improvements over the Pound source base, including:

• 2x faster operation
• the per-request thread creation is replaced with a fixed-size thread pool, with a common workitem queue and automatic pool sizing at startup time, to keep the memory usage constant and for faster operation under LinuxThreads.
• added features - the 'synch' cookie mode and the cookie insert mode (see the data sheet for details - CatSwitchesHlb).

Changes

• none - this is the first release of HLB.

Known Problems

• in testing HLB under high load, a problem was found that has been traced back to packet loss somewhere in the network stack, likely in the virtual network adapter mechanism in XEN. This is not related to HLB as such and is documented in detail in the Bugzilla database SCR 577, now resolved.
• the performance tests are limited to displaying the results (without checking them) or disabled, due to the problem described above.
• the /usr volume image has unused space (50Mb or so) that could be trimmed to reduce the volume size. This is not likely to be a problem, since the /usr volume is shared and no copies of it are made when instances of HLB are used.

-- LeoKalev - 02 Mar 2006