Re: [squid-users] Maximum disk cache size per worker

On 22/03/2013 7:21 p.m., Sokvantha YOUK wrote:
> Dear Amos,
>
> I am pretty sure love to go down to try SMP equivalent of a CARP
> peering. Please guide me.

The design is laid out here with config files for the pre-SMP versions
of Squid:
  http://wiki.squid-cache.org/ConfigExamples/MultiCpuSystem

The SMP worker version of that is only slightly different. There is only
one "squid" started using a single main squid.conf containing a series
of if-conditions assigning each worker to a frontend or backend
configuration file like so:

squid.conf:
   workers 3
   if ${process_number} = 1
   include /etc/squid/backend.conf
   endif
   if ${process_number} = 2
   include /etc/squid/backend.conf
   endif
   if ${process_number} = 3
   include /etc/squid/frontend.conf
endif

The backend can share one config file by using ${process_number} in all
the unique '1' , '2' places (hostname, cache_dir, last digit of port
number etc)

The frontend must reference the backend without using ${process_number}.
And can also have rock cache_dir to service small objects out of
quickly, although YMMV on this.

You can expand this out with multiple frontend if you like, or with more
than 2 backends.

Amos

> ---
> Regards,
> Vantha
>
> On Fri, Mar 22, 2013 at 1:13 PM, Amos Jeffries <squid3_at_treenet.co.nz> wrote:
>> On 22/03/2013 4:39 p.m., Alex Rousskov wrote:
>>> On 03/21/2013 08:11 PM, Sokvantha YOUK wrote:
>>>
>>>> Thank you for your advice. If I want large files to be cached when it
>>>> fist seen by worker, My config should change to first worker that see
>>>> large file and cache it else left it over to remaining worker for rock
>>>> store worker?
>>> Your OS assigns workers to incoming connections. Squid does not control
>>> that assignment. For the purposes of designing your storage, you may
>>> assume that the next request goes to a random worker. Thus, each of your
>>> workers must cache large files for files to be reliably cached.
>>>
>>>
>>>> I don't want cached content to be duplicated
>>>> among AUFS cache_dir and I want to use the advantage of rock store
>>>> which can be shared within worker on SMP deployment.
>>> The above is not yet possible using official code. Your options include:
>>>
>>> 1. Do not cache large files.
>>>
>>> 2. Cache large files in isolated per-worker ufs-based cache_dirs,
>>> one ufs-based cache_dir per worker,
>>> suffering from false misses and duplicates.
>>> I believe somebody reported success with this approach. YMMV.
>>>
>>> 3. Cache large files in SMP-aware rock cache_dirs,
>>> using unofficial experimental Large Rock branch
>>> that does not limit the size of cached objects to 32KB:
>>> http://wiki.squid-cache.org/Features/LargeRockStore
>>>
>> 4. Setup the SMP equivalent of a CARP peering hierarchy with the frontend
>> workers using shared rock caches and the backend using UFS. This minimizes
>> cache duplication. But in the current SMP code requires disabling loop
>> detection (probably not a good thing) and some advanced configuration
>> trickery.
>> If you want to actually go down that path let me know and I'll put the
>> details together.
>>
>> Amos
>
>
Received on Fri Mar 22 2013 - 10:05:32 MDT