Datasheet

“main” (Installation and Administration) — 2004/6/25 — 13:29 — page 603 — #629
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Internet
The easiest way to determine the needed cache size is to consider the maxi-
mum transfer rate of the connection. With a 1 Mbit/s connection, the maxi-
mum transfer rate is 125 KB/s. If all this traffic ends up in the cache, in one
hour it would add up to 450 MB and, assuming that all this traffic is gener-
ated in only eight working hours, it would reach 3.6 GB in one day. Because
the connection is normally not used to its upper volume limit, it can be as-
sumed that the total data volume handled by the cache is approximately
two GB. This is why two GB of disk space is required in the example for
Squid to keep one day’s worth of browsed data cached.
RAM
The amount of memory (RAM) required by Squid directly correlates to the
number of objects in the cache. Squid also stores cache object references
and frequently requested objects in the main memory to speed up retrieval
of this data. Random access memory is much faster than a hard disk.
In addition to that, there is other data that Squid needs to keep in memory,
such as a table with all the IP addresses handled, an exact domain name
cache, the most frequently requested objects, access control lists, buffers,
and more.
It is very important to have sufficient memory for the Squid process, be-
cause system performance is dramatically reduced if it must be swapped to
disk. The cachemgr.cgi tool can be used for the cache memory manage-
ment. This tool is introduced in Section 25.3.7 on page 613.
CPU
Squid is not a program that requires intensive CPU usage. The load of the
processor is only increased while the contents of the cache are loaded or
checked. Using a multiprocessor machine does not increase the perfor-
mance of the system. To increase efficiency, it is better to buy faster disks
or add more memory.
25.3.4 Starting Squid
Squid is already preconfigured in SUSE LINUX, so you can start it easily
right after installation. A prerequisite for a smooth start is an already con-
figured network, at least one name server, and Internet access. Problems
can arise if a dial-up connection is used with a dynamic DNS configura-
tion. In cases such as this, at least the name server should be clearly en-
tered, because Squid does not start if it does not detect a DNS server in
/etc/resolv.conf.
603SUSE LINUX Enterprise Server