RE: [squid-users] Extreme delays on cache misses

Well, your stats don't look too bad. Is this representative of what you
normally see? It looks like your misses are taking about as long as DNS
requests (and misses are only taking a fifth of a second). On the accesses
that are timing out, have you verified that the sites are indeed accessible?
Spyware often tries to access pages that don't exist any more.

Another useful cachemrg page is "Cache Utilization" (about 2/3 of the way
down the page). It shows requests per second and bandwidth usage.

Chris

-----Original Message-----
From: Shawn Wright [mailto:swright@sls.bc.ca]
Sent: Tuesday, November 23, 2004 11:08 AM
To: squid-users@squid-cache.org
Subject: [squid-users] Extreme delays on cache misses

This may not be a squid issue, but I'm hoping to find some assistance
in deciphering cachemgr output to determine if squid is part of the
problem.

Here is the situation:

Approx 500 client PCs
10Mb full duplex internet feed, through a Linux firewall, with peak traffic
of 5Mb/s, avg of .
Temporary proxy was a squid box running win2k on a PII/266. I realize
this is pretty slim hardware for the above load, but it was performing
surprisingly well until a few weeks ago.
We were running low on RAM in our firewall, so it was taken down and
upgraded. We are fairly certain it is no longer a bottleneck.
We have replaced the squid box with a 2.4G box, and saw little
performance improvement. At times, responses were good, at others,
so slow that we would see timeouts. Access log showed many cache
misses with elapsed times over 20 seconds. In recent weeks, we've
had some client PCs infected with spyware hammering our proxy with
up to 80 hits per second (each client), all being denied, and generating
hundreds of Mb of extra logs each day. (we require all access to be
authenticated). At present, all of these machines have been located
and shutdown.

Below is the cachemgr out for general info - I'd appreciate any tips on
what to focus on. THanks.

Start Time: Tue, 23 Nov 2004 17:21:00 GMT
Current Time: Tue, 23 Nov 2004 20:01:05 GMT

Connection information for squid:
        Number of clients accessing cache: 244
        Number of HTTP requests received: 150248
        Number of ICP messages received: 0
        Number of ICP messages sent: 0
        Number of queued ICP replies: 0
        Request failure ratio: 0.00
        Average HTTP requests per minute since start: 938.6
        Average ICP messages per minute since start: 0.0
        Select loop called: 4937900 times, 1.945 ms avg
Cache information for squid:
        Request Hit Ratios: 5min: 26.5%, 60min: 28.9%
        Byte Hit Ratios: 5min: 15.1%, 60min: 12.1%
        Request Memory Hit Ratios: 5min: 11.5%, 60min: 8.4%
        Request Disk Hit Ratios: 5min: 47.4%, 60min: 44.0%
        Storage Swap size: 1843193 KB
        Storage Mem size: 68536 KB
        Mean Object Size: 15.19 KB
        Requests given to unlinkd: 13646
Median Service Times (seconds) 5 min 60 min:
        HTTP Requests (All): 0.08729 0.10281
        Cache Misses: 0.15048 0.19742
        Cache Hits: 0.01469 0.00000
        Near Hits: 0.12106 0.15888
        Not-Modified Replies: 0.00000 0.00000
        DNS Lookups: 0.16304 0.09117
        ICP Queries: 0.00000 0.00000
Resource usage for squid:
        UP Time: 9604.937 seconds
        CPU Time: 2047.047 seconds
        CPU Usage: 21.31%
        CPU Usage, 5 minute avg: 2.34%
        CPU Usage, 60 minute avg: 27.24%
        Maximum Resident Size: 130388 KB
        Page faults with physical i/o: 33227
Memory accounted for:
        Total accounted: 92599 KB
        memPoolAlloc calls: 17735541
        memPoolFree calls: 17014828
File descriptor usage for squid:
        Maximum number of file descriptors: 2048
        Largest file desc currently in use: 325
        Number of file desc currently in use: 187
        Files queued for open: 0
        Available number of file descriptors: 1861
        Reserved number of file descriptors: 100
        Store Disk files open: 4
Internal Data Structures:
        121688 StoreEntries
         15119 StoreEntries with MemObjects
         15115 Hot Object Cache Items
        121341 on-disk objects

Generated Tue, 23 Nov 2004 20:01:05 GMT, by
cachemgr.cgi/2.5.STABLE7-NT@it-temp4512
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Shawn Wright, I.T. Manager
Shawnigan Lake School
http://www.sls.bc.ca
swright@sls.bc.ca
Received on Tue Nov 23 2004 - 14:22:59 MST