Re: [squid-users] Re: cache_mem question

On Sunday 04 May 2003 19.33, Rodsak Promrattanakul wrote:
> ----- Original Message -----
> From: "Henrik Nordstrom" <hno@squid-cache.org>
>
> > If you have additional questions please be a bit more specific on
> > what you want to know.
>
> 1.When Squid recieved Object which uncacheable , what 'll squid do?

Forward it to the client.

While the object is forwarded parts may temporary be in cache_mem (a
few KB)
>
> 2.When Squid recieved Object which cacheable ,Squid keep Object
> in RAM (Hot Object ) and concurrently Squid keep Object in
> Disk(Cold Object) : Right or Wrong?

Yes, unless the object is too large to be kept in memory.

> 3.cache_mem content is In-transit-Object , Hot-Object and
> Negative-Object , so what is In-transit-Object ?

In-transit objects is objects currently being forwarded to a client.

> what is Negative-Object ?

Error responses etc.

> 4.storeEntry is index for indicate Object ?

Each object have one StoreEntry.

> 5.Squid use index to indicate Object .Where is the index , is it in
> memory only ? Is it in cache_mem or not?

memory only. not related to cache_mem. cache_mem only keeps object
data (body).

> 6.storeEntry have no limit ?

Each StoreEntry is fixed in size (ca 100 bytes). There is as many
StoreEntry as needed.

> If it have no limit ,what happen if Squid have many object?

There will be many objects in your cache, as many as there is space
for. Each object will have a StoreEntry. The amount if StoreEntry is
intirectly limited by the size of yoru cache and cache_mem.

> If storeEntry have limit, what is replacement policy?

The replacement policy is used to determine which objects to evict
from the cache to make room for more (either cache_mem or disk
cache).

> 7.Can cold object was removed ? What ' case ? And What happen
> about it's index ?

When an object is removed it is deleted from disk, cache_mem and the
index.

> 8.What should I do if my cache_dir is full ?

Nothing. Squid will automatically delete objects to make room for more
when needed.

> 9.Unlinkd used for unlinking old index or old Object?

Object.

> 10.When I reconfig cache_mem (in case cache_mem was decrease), then
> I run squid -k reconfigure .
> Which content was removed?

Data stored in cache_mem.

> What happen about - index which indicate object ?
> - Hot Object ?

Nothing, execpt if negatively cached entries are removed from
cache_mem (in such case they are also deleted from the index, as
negatively cached objects do not have a copy on disk)

> What is an example of Semi-Hot Object?

An object for which there recently was a TCP_HIT is one example. There
is many other.

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