Bug 41809

Bug: 41809

Impact:

Informational

Product:

GemStone/S 64 Bit

Versions:

3.7.1, 3.7, 3.6.8, 3.6.7, 3.6.6, 3.6.5, 3.6.4, 3.6.3, 3.6.2, 3.6.1, 3.6, 3.5.8, 3.5.7, 3.5.6, 3.5.5, 3.5.4, 3.5.3, 3.5.2, 3.5.1, 3.5, 3.4.5, 3.4.4, 3.4.3, 3.4.2, 3.4.1, 3.4, 3.3.9, 3.3.8, 3.3.7, 3.3.6, 3.3.5, 3.3.4, 3.3.3, 3.3.1, 3.3, 3.2.16, 3.2.15, 3.2.14, 3.2.13, 3.2.12, 3.2.11, 3.2.10, 3.2.9, 3.2.8.1, 3.2.8, 3.2.7, 3.2.6, 3.2.5, 3.2.4, 3.2.3, 3.2.2, 3.2.1, 3.2, 3.1.0.6, 3.1.0.5, 3.1.x, 3.0.1, 3.0, 2.4.8, 2.4.7, 2.4.6, 2.4.5.1, 2.4.5, 2.4.4.8, 2.4.4.7, 2.4.x, 2.3.1.6, 2.3.1, 2.3, 2.2.6.5, 2.2.5.4, 2.2.x, earlier versions

Platform:

All

Fixed In:

n/a

Slow checkpoints if much more AIO page servers than Free Frame page servers

If you increase the number of AIO page servers, but leave the number of free frame page servers at 1, under some conditions of heavy load the checkpoints may take a very long time to complete, an hour or more.

The problem is that the page servers operate on separate regions within the cache, dividing the cache amoung the total number of page servers. If there is only one free frame page server, it operates on the whole cache, so it will return pages to one region at a time as it progresses through the cache, and these free pages may be used for new work.  On checkpoint, when the AIO page servers write out all modified pages, most of these pages will be in one region, so the remaining page servers will sit idle waiting for one page server to complete writing.

Workaround

Ensure that the SHR_NUM_FREE_FRAME_SERVERS is the same as STN_NUM_LOCAL_AIO_SERVERS.

In later versions this is the default.