[squid-users] HDD/RAM Capacity vs store_avg_object_size

[Alex Rousskov]

On 07/13/2017 10:17 AM, bugreporter wrote:

> But what is this mean value size? Do you have any update to share please?

I do not know what value the wiki page authors used, but I suspect it
was close to 13K. I believe Amos has already suggested that you use the
actual cachable response size mean from your environment, and I agree
with that suggestion (although it is not trivial to follow). There is no
and cannot be an "authoritative" mean value that works well for all
environments.


> According to your answer, HTTP headers are not part of the in-memory index
> and we have to consider StoreEntry and LruNode (or equivalent) only. Can you
> please be more specific about what inputs of cachemgr "mem" report should we
> take into account?

Not without doing research. I also hesitate recommending mgr:mem output
for folks that cannot or do not want to find answers about it by
studying the associated code themselves -- it is just too easy to
misinterpret those low-level stats!

You may be able to figure it out on your own without relying on
low-level stats by disabling the memory cache, filling your disk cache
with, say, 1'000, 10'000, and then 100'000 identical or similar objects,
and measuring memory usage growth. You can then try to confirm your
findings by comparing them with the previously collected mgr:info,
mgr:storedir, and mgr:mem output for each stage of the experiment.

Alex.