Re: [squid-users] Memory usage...

John Doe wrote:
> From: Amos Jeffries <squid3_at_treenet.co.nz>
>> Actual experienced measurements from some general-purpose web caches. On 32-bit
>> systems. Newer 64-bit systems have reported a 15MB/GB requirement.
>> It's the amount of data seen to be used for index meta data and other types of
>> index.
>> ...
>> The average average size of web traffic items here is around 64KB.
>> ...
>> Assuming what sized object?
>> An (empty) web HTML 0.9 page has as few as 14 bytes. XML files likewise may only
>> have 20 bytes or so.
>> For a cache full of those (think dynamic web app gone downright evil), you would
>> need about 1MB memory per MB of cache.
>> Whereas at the other end, if you are caching only ISO DVD images. Your memory
>> drops to under 1KB memory per GB of cache.
>> Its a 'rule-of-thumb', which means we recommend to newbies that they use it to
>> plan and configure their system memory. And over time watch their squid to see
>> how it needs adjusting for best performance.
>
> Hi,
>
> replying to an old post...
> We finaly bought our squid servers (540GB of disk, 48GB of RAM)... and I am a bit scared...
> I know it is just a rule of thumb but, if I re-apply the formula (for 64KB average object sizes) and, having 16KB average object sizes, multiply the required RAM by 4 (64/16), I get...
>
> -------------------------+----------------+-------------
> cache_dir (best) | RAM for DISK | cache_mem
> -------------------------+----------------+-------------
> 613 GB ( 306 GB) | 36 GB | 1 GB
> 544 GB ( 272 GB) | 32 GB | 6 GB
> 476 GB ( 238 GB) | 28 GB | 11 GB
> 408 GB ( 204 GB) | 24 GB | 16 GB
> 340 GB ( 170 GB) | 20 GB | 21 GB
> 271 GB ( 135 GB) | 16 GB | 26 GB
> 203 GB ( 101 GB) | 12 GB | 31 GB
> 135 GB ( 67 GB) | 8 GB | 36 GB
> 66 GB ( 33 GB) | 4 GB | 41 GB
> -------------------------+----------------+-------------
>
> do these values look mostly correct?
>

Sort of. Though you need to account for cache_mem indexing too.

The rule-of-thumb applies to sum(cache_dir)+cache_mem.
When dealing with GB of cache_mem it starts to be noticed.

Amos

-- 
Please be using
   Current Stable Squid 2.7.STABLE7 or 3.0.STABLE24
   Current Beta Squid 3.1.0.17