BoKS: mind your log files!

2011-04-06 00:00:00

BoKS' main log file for transactions is $BOKS_data/LOG. The way BoKS handles this file is configured using the logadm command. Specifically, this is done using two distinct variables:

• -T Log file threshold size in kBytes
• -M Log file maximum size in kBytes

For example:

$ suexec logadm -V
Log file size limit before backup:       3000 kbytes
Absolute maximum log file size:          100000 kbytes

$ suexec logadm -lv
Primary log directory:                   /var/opt/boksm/data
Backup log directory:                    /var/opt/boksm/archives

What this means is that:

• Once $BOKS_data/LOG reached 3MB in size, the file will be rotated into $BACKUP_dir.
• If $BOKS_data/LOG cannot be rotated, it will be allowed to grow to 100MB and then quit.

First off, this means that it's not just $BOKS_data that you need to monitor for free space! $BACKUP_dir is equally important because once the -M threshold is reached BoKS will simply stop logging. But then there's something else!

Did you know that BoKS is hard coded for a maximum of 64 log rotations per day? This is because the naming scheme of the rotated logs is: L$DATE[",#,%,',+,,,-,.,:,=,@A-Z,a-z]$DATE. Once BoKS reaches L$DATEz$DATE it will keep on re-using and overwriting that file because it cannot go any further! This means that you could potentially lose a lot of transaction logging.

The current work around for this problem is to set your logadm -T value large enough to prevent BoKS from ever reaching the "z" file (the 64th in line). Of course the real fix would be to switch to a different naming scheme that is more flexible and which allows a theoretically unlimited amount of log rotations.

The real fix has been requested from FoxT and is registered as RFC 081229-160335. This fix has been confirmed as being part of BoKS v6.6.1 (per build 13 I am told).

kilala.nl tags: boks, sysadmin,

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