John Doe wrote:
From: Amos Jeffries <squid3@xxxxxxxxxxxxx>
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
