I added the script to a gist just to keep it reachable: https://gist.github.com/elico/dfccc0905bc223c68c483e5074a6484a Eliezer From: squid-users <squid-users-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Andrey K
Sent: Thursday, June 22, 2023 12:09
To: Alex Rousskov <rousskov@xxxxxxxxxxxxxxxxxxxxxxx>
Cc: squid-users@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: Enable caching On 4/5/23 09:27, Alex Rousskov wrote:
> On 4/5/23 06:07, Andrey K wrote:
>
>> Previously, caching was disabled on our proxy servers. Now we need to
>> cache some content (files about 10 MB in size).
>> So we changed the squid.conf:
>
>> cache_dir ufs /data/squid/cache 32000 16 256 max-size=12000000
>>
>> We have 24 workers on each proxy.
>
> UFS-based cache_dirs are not supported in multi-worker configurations
> and, in most cases, should not be used in such configurations. The
> combination will violate basic HTTP caching rules and may crash Squid
> and/or corrupt responses.
>
>
>> We saw that some requests were taken from the cache, and some were not.
>> The documentation says:
>> "In SMP configurations, cache_dir must not precede the workers option
>> and should use configuration macros or conditionals to give each
>> worker interested in disk caching a dedicated cache directory."
>
> The official documentation quoted above is stale and very misleading in
> modern Squids. Ignore it. I will try to find the time to post a PR to
> fix this.
Done at https://github.com/squid-cache/squid/pull/1394
Alex.
>> So we switched to a rock cache_dir:
>> cache_dir rock /data/squid/cache 32000 max-size=12000000
>>
>> Now everything seems to be working fine in the test environment, but I
>> found limitations on the RockStore
>> (https://wiki.squid-cache.org/Features/RockStore:
>> "Objects larger than 32,000 bytes cannot be cached when cache_dirs are
>> shared among workers."
>
> The Feature/RockStore page is stale and can easily mislead. In general,
> Feature/Foo wiki pages are often development-focused and get stale with
> time. They cannot be reliably used as a Squid feature documentation.
>
>
>> Does this mean that RockStore is not suitable for caching large files?
>
> No, it does not. Rock storage has evolved since that Feature page was
> written. You can see the following wiki page discussing evolved rock
> storage design, but that page probably has some stale info as well:
> https://wiki.squid-cache.org/Features/LargeRockStore
>
>
>> Should I switch back to the UFS and configure 24 cache_dirs
>
> If everything is "working fine", then you should not. Otherwise, I
> recommend discussing specific problems before switching to that
> unsupported and dangerous hack.
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