Keeping Tabs On The DynaCache
The DynaCache offers a number of monitoring methods: DynaLink LEDs, configurable
reachability checks, Telnet access to status information, stored log file
retrieval, and SNMP traps.
DynaLink LEDs, ping, trace route, and port stats are available to help
diagnose connectivity problems. The most important LED is the bypass light.
The DynaLink continuously monitors reachability with a "watchdog" and
invokes bypass when the DynaCache appears unresponsive. During our evaluation,
this happened nightly at 1:54 am when the cache briefly busied itself
during logfile roll-over. Tech support disabled our watchdog to avoid
bypass while investigating the problem; we suspect timer adjustment might
do the trick.
Squidlog
Problem detection and diagnosis were facilitated by logfiles: "squidlogs"
that detail client requests, syslogs that identify OS-related events, and
errorlogs that identify cache-related events. The CLI doesn't include hooks
to disable logging or limit file size, but can list, view, or delete logfiles.
You can peek at the squidlog
with the "show cache squidlog" command; this produces semi-real-time
results since the file is buffered. Most admins will prefer to FTP
these files from /var/log and perform off-line analysis, such as converting
UNIX time_t values.