On 29.05.2012 09:45, Beto Moreno wrote:
Sorry, I didn't finish this post.
1 question, I will setup a cache server with squid 2.7.x, the server
will have 8GB of ram, the biggest service will be squid, I'm thinking
in 4GB for squid, 4GB other services.
I have seen that squid use part of the memory to save objects and
some
times he return the cache from memory or disk, memory is faster we
know this, them this is one reason
that I want to give more memory to squid.
Is what I understand, them if I'm right, what happen once U reboot my
server?
What does squid to the object in memory?
Squid tries to save what it can and terminate cleanly in the time
allowed (shutdown_timeout).
Do I lost them?
There is a very important concept to keep in mind here which is often
overlooked:
*** Cache is temporary storage ***. Emphasis on "temporary". It is
Constantly renewed from network sources.
As a result no content is ever "lost". Even should you completely erase
the cache contents and restart from a clean-slate, everything is still
available from the relevant origins/master server somewhere out on the
network.
Or haven't understand how squid use the memory?
You seem to understand the usage okay. But you are fixated a bit on
hoarding data.
The only side-effect of rebooting the server is a short "full" outage
of service, and a short period of slightly slower service as the caches
are re-filled.
This may sound bad at first glance, but it is a tradeoff between
network and disk re-builds. Even if everything was saved to disk across
the reboot there is still a slow period from disk I/O latency and CPU to
re-populate the memory indexes. Versus network lag of fetching a clean
copy.
Squid has automatic client new-connection damping/buffering to cope
with both these periods and DoS situations without actually loosing
clients requests.
Amos
