bijayant kumar wrote:
Bijayant Kumar
--- On Thu, 31/7/08, Amos Jeffries <squid3@xxxxxxxxxxxxx> wrote:
From: Amos Jeffries <squid3@xxxxxxxxxxxxx>
Subject: Re: Some queries about cache_peer
To: bijayant4u@xxxxxxxxx
Cc: "squid users" <squid-users@xxxxxxxxxxxxxxx>
Date: Thursday, 31 July, 2008, 5:09 PM
bijayant kumar wrote:
From: Amos Jeffries <squid3@xxxxxxxxxxxxx>
Subject: Re: Some queries about
cache_peer
To: bijayant4u@xxxxxxxxx
Cc: "squid users"
<squid-users@xxxxxxxxxxxxxxx>
Date: Thursday, 31 July, 2008, 9:31 AM
Hello list,
I tried to set up cache_peer, but i could not
understand that it has setup
or not. Please give some inputs.
Scenario:-
I have setup three proxy-servers.squid 3.0.7
Stable
proxy1 192.168.99.134
proxy2 192.168.99.135
proxy3 192.168.99.121
Lan Computer 192.168.99.23.
On my Lan Computer, i have configured proxy in
my
browser as
192.168.99.134 ie proxy1. All request first go
to
proxy1.
In Proxy1 squid.conf:-
cache_peer 192.168.99.135 parent 3128
3130
proxy-only default
cache_peer 192.168.99.121 parent 3128
3130
proxy-only
cache_peer_domain 192.168.99.135 .com
cache_peer_domain 192.168.99.121 .net
In proxy2 and proxy3 no cache_peer is
configured.
I can browse the web. But i didnt understand
the
working. I have some
queries regarding this scenario:
If the page is not in any of the proxy server,
then
which proxy server
will go to internet and fetch for the user. I
mean if
user access any
".net" domain then the request will
come to
the proxy1 first, it will
query to the proxy3, if its there it will be
delivered
else the page will
be fetched from the internet ,Same is for the
".com" domain right?
Usually. If netdb/icmp has been enabled squid will
keep
records of
response times and go to whichever of peer/web
responds
fastest. thinking
fastest available service is usually best to use.
Check your access.log for info on which is being
selected
for each request.
Then my question is,
1) which server will query to the internet for
the
page which is not in
the cache ie ".net" dedicated server
or the
main proxy1 server?
Under only cache_peer_domain, maybe both. Use
'never_direct' to force
requests to go via peers.
If i use 'never_direct' option then if parent
cache servers will go down then no body will be able to
browse the web. And if i will not use 'never_direct'
option then fetching of object will be done by proxy1,if
object not found in any cache(proxy2/proxy3), am i right?
Yes.
2) The new page will be written to the which
cache,
proxy1 or
proxy2/proxy3
'proxy-only' prevents caching at proxy1 if
request
came from peer. If
request came from web DIRECT then it can be cached
at
proxy1 and used
later.
In my configuration, proxy1 will query to the internet
for new objects and hence the cache will be populated of
proxy1 only, no matter it is of ".net" domain or
of ".com" domain. Then the new entry of
".net" and ".com" domain will never be
written to the cache of the dedicated caching server for the
same.
If i am right in my analogy then can you please
suggest me to how to avoid this situation. I mean that
".net" cache will be written to ".net"
dedicated server(proxy3) and ".com" cache will be
written to the proxy2.
In squid you only have a choice of peers vs DIRECT.
Your config earlier was workable, in which case squid will
make that
choice every request. Usually going peers, but sometimes
going DIRECT.
Or you can force a choice yourself with never_direct
(opposite is
always_direct, but its clear to me you don't want
that).
It's up to you.
To decide if a cache of 100% .com traffic is worth the
small risk of no
access to .com at all when proxy2 goes down. Which is only
2x the same
risk of proxy1 going down by itself anyway.
Keeping in mind that a quick admin reconfigure of proxy1
(commenting out
the proxy2 lines) can restore access while proxy2 is
debugged about why
it went down.
It means that this configuration will not serve my purpose of using cache_peer. I also can not afford of any down time also.
I wanted to use proxy servers in my network which are 2 to 3 in numbers, share their cache among them. To achieve this setting shall i use DNS round robin or squid round robin along with the cache_peer settings in all the three server's squid.conf ? Can you give me some input to achieve this, it would be great help.
To mesh 2-3 squid together with high reliability and efficiency the best
option is probably 'carp'. AFAIK, thats the only thing you need to add
on the cache_peer line for it to work. Dropping the 'proxy-only' option
to share caches lets the highest usage objects be in the proxy closest
to the client.
That will then query all peers and the local cache for an object then go
direct.
You can then set DNS up to have one name configured in all clients and
point at 2-3 IP addresses for reasonable failover if any break.
Amos
--
Please use Squid 2.7.STABLE3 or 3.0.STABLE8
