On 11/10/17 23:31, Victor Sudakov wrote:
Alex Rousskov wrote:
On 10/10/2017 07:50 PM, Victor Sudakov wrote:
When updating several almost identical FreeBSD hosts via a
squid-3.5.27 proxy, I expect to see lots of HITs, because the patches
on the update server should be identical too.
However, I see lots of TCP_REFRESH_UNMODIFIED lines, and only
occasional HIT statuses.
There are many kinds of "hits":
* If your primary concern is data transfer/bandwidth usage, then you
should focus on so called byte hits. TCP_REFRESH_UNMODIFIED is
essentially one of those because the origin server sends a tiny
headers-only response to Squid.
My primary concern is bandwidth usage. You are saying that the
TCP_REFRESH_UNMODIFIED transaction means that the bulk of the data is
not transferred from Webserver to Squid, only the headers are fetched?
Yes.
If you look at this line:
1507630625.515 448 212.73.124.12 TCP_REFRESH_UNMODIFIED/200 980593 GET http://update6.freebsd.org/to-10.4-RELEASE/i386/bp/1195d725efce75f0db6317f507d8a9514f35613c7466673a86db23100bd6fa77-c4150431df5b14b15546b3db5e30f2bd2c35d6d52812f057dc101fab20847324 - HIER_DIRECT/198.148.79.66 application/octet-stream
There cannot be 980593 bytes of headers? What kind of gigantic header
does it make?
That is header only between Squid and server (REFRESH_UNMODIFIED), with
full object delivered to the client (final status "200").
...
According to your pasted log and HTTP messages, the GET request URL that
resulted an "X-Cache-Lookup: MISS" response header does not match any of
the logged URLs; even the host part of the URL does not match.
Of course, there are just unrelated examples. There are thousands of
fetches from update*.freebsd.org
So you just posted them to waste everybody on this lists bandwidth?
Thanks, and kind of ironic given your "problem".
To be sure that you are comparing apples to apples, you would need
to log the X-Cache-Lookup response header to access.log (or enable
ALL,2 debugging to see headers and/or collect packet traces).
I don't think the freebsd-update cares about the X-Cache-Lookup
response, I'm just trying to save bandwidth and don't quite like the
result.
The X-Cache* headers are debug output from Squid. Of course the updater
software does not care about it ... you do, sort of anyway since it
shows whether server bandwidth was involved. They do not show REFRESH,
so MISS means a server was contacted for _something_ and HIT means local
cache only was used.
Amos
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