Re: [squid-users] Swap-in, Swap-out and HotObjects...

tc8@staffs.ac.uk wrote:
>
> Hi,
>
> I am a little confused!
>
> Does Squid take objects off the disk and store them in memory (as a
> hot object) and then at a later date take the same object out of
> memory and put it BACK on the disk...
>
> Or does the object never leave the disk but is copied into memory?

Neither.

Squid never brings an object back into the hot objects memory cache
after it's been swapped out to disk.

Hot objects are popular objects that have recently been stored in
memory. They always come from the network, never from disk. This is
what cache_mem is used for. It usually uses an LRU replacement policy.

Your OS probably handles keeping older disk objects cached in memory on
an as-needed and as-available basis. That's what the OS buffer/cache
layer is for.

Squid removes objects from disk as space is needed by new objects, based
on the replacement policy you've selected. LRU (least recently used) is
the default.

-- 
Joe Cooper <joe@swelltech.com>
Web caching appliances and support.
http://www.swelltech.com