Squid_ The Definitive Guide - Duane Wessels [139]
shutdown: Shut Down the Squid Process*
This is one of the few cache manager functions that doesn't simply display some information. Rather, this "page" allows you to shut down Squid remotely. To allow shutdown via the cache manager, you must assign it a password with the cachemgr_passwd (see Section 14.2.2) directive in squid.conf. Without a password, the shutdown operation is disabled (but you can still use squid -k shutdown).
Because the cache manager has very weak security—passwords are sent in cleartext—I don't recommend enabling this operation.
offline_toggle: Toggle offline_mode Setting*
This is another function that allows you to control Squid, rather than simply receive information. It also requires a password (see Section 14.2.2) in order to become active.
Each time you request this page, Squid toggles the offline_mode setting. Squid reports the new setting on your screen and in cache.log.
info: General Runtime Information
This page provides a lot of basic information about the way that Squid is operating. It is a good starting point for using the cache manager and for tracking down performance problems.
At the top, you'll see the release version (e.g., Version 2.5.STABLE4) and two timestamps: the starting and current times. For example:
Squid Object Cache: Version 2.5.STABLE4
Start Time: Mon, 22 Sep 2003 03:10:37 GMT
Current Time: Mon, 13 Oct 2003 10:25:16 GMT
Following that, you'll see seven different sections. The first section, Connection information, displays a few statistics about the number and rate of connections, and the number of cache clients:
Connection information for squid:
Number of clients accessing cache: 386
Number of HTTP requests received: 12997469
Number of ICP messages received: 16302149
Number of ICP messages sent: 16310714
Number of queued ICP replies: 0
Request failure ratio: 0.00
Average HTTP requests per minute since start: 423.7
Average ICP messages per minute since start: 1063.2
Select loop called: 400027445 times, 4.601 ms avg
Number of clients accessing cache
Here, "client" actually means IP address. Squid assumes that each client has a unique IP address.
Number of HTTP requests received
The total number of HTTP requests since Squid was started.
Number of ICP messages received
The total number of ICP messages received since Squid was started. Note, received messages includes both queries and responses. These values don't include HTCP messages, however.
Number of ICP messages sent
The total number of ICP messages sent since Squid was started. Note, received messages includes both queries and responses. Doesn't include HTCP messages. Most likely, your sent and received counts will be about the same.
Number of queued ICP replies
ICP messages are sent over UDP. The sendto( ) system call rarely fails, but if it does, Squid queues the ICP message for retransmission. This counter shows how many times an ICP message was queued for retransmission. Most likely, you'll see 0 here.
Request failure ratio
The failure ratio is a moving average ratio between the number of failed and successful requests. In this context, a failed request is caused by either a DNS error, TCP connection error, or network read error. When this ratio exceeds 1.0—meaning Squid returns more errors than successful responses— Squid goes into hit-only mode. In this mode, Squid returns ICP_MISS_NOFETCH instead of ICP_MISS. Thus, your neighbor caches that use ICP won't forward cache misses to you until the problem goes away.
Average HTTP requests per minute since start
This value is simply the number of HTTP requests divided by the amount of time Squid has been running. This average doesn't reflect short-term variations in load. To get a better instantaneous load measurement, use the 5min or 60min page.
Average ICP messages per minute since start
The number of ICP queries received by Squid divided by the amount of time that it has been running.
Select loop called
This number is probably meaningful only