[squid-users] Question on Squid internals

Hi,

I'm totally puzzled as to how the LRU cache replacement policy has been
implemented in Squid.

Here's my situation.

............................................................
squid.conf-
cache_dir aufs /data01/aufs01 100000 16 256

$ pwd
/data01/aufs01/00/00

$ ll 001000FF
-rw-r----- 1 squid squid 20687 Dec 20 18:00 001000FF // some webpage that Squid cached

$ head 001000FF
����
      
��0^�<D��,��.K��.K����������������
`;http://some-urlaccept-encoding="gzip,deflate"HTTP/1.1
200 OK
Date: Mon, 21 Dec 2009 02:00:31 GMT
Server: Apache-Coyote/1.1
Set-Cookie: some cookie
Set-Cookie: some cookie
Set-Cookie: some cookie
P3P: CP="IDC DSP COR CUR ADMa DEVa TAIa PSAa PSDa CONo TELi OUR OTRi IND PHY ONL UNI FIN COM NAV INT DEM CNT STA PRE"
Set-Cookie: some cookie
Set-Cookie: some cookie
Set-Cookie: some cookie
Path=/
............................................................

So there is a cached page for the url: "some-url" on the disk.

............................................................
$ curl -H "User-Agent: some useragent" -H
"Accept-Encoding: gzip,deflate" "http://some-url"

Squid access.log -

xxx.xxx.xxx.xxx - - [23/Dec/2009:11:03:31 -0800] "GET http://some-url
HTTP/1.1" 200 19114 "-" "-" "-" "gzip,deflate"
TCP_MISS/FIRST_UP_PARENT 446

$ ll 001000FF
ls: 001000FF: No such file or directory
............................................................

A page that is just 3 days old encountered a cache miss, even though the
cached page is physically present on the disk. Could somebody explain
why this has happened? The exact same URL is requested from the command
line and Squid has removed its copy of the page after the command
execution. If the copy has become stale, going by the refresh_pattern
rules, a TCP_REFRESH_MISS should have got logged instead of TCP_MISS.
Its really weird that the copy on the disk was deleted, and a TCP_MISS
was reported.

Appreciate your response.
TIA!

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Received on Wed Dec 23 2009 - 20:47:23 MST