Re: [squid-users] Squid limits and hardware spec

On Thu, 2004-12-02 at 16:04, Matus UHLAR - fantomas wrote:
> > >On Mon, 2004-11-29 at 11:32, Martin Marji Cermak wrote:
> > >
> > >>Hello guys,
> > >>I have been playing with Squid under a heavy load and there are some
> > >>stats.
> > >>I am trying to maximise the "Byte Hit Ratio" value. I got 13% average,
> > >>but I am not happy about this number - I want it higher (how to do it?).
> > >>There are thousands of ADSL clients using the cache and I want to know
> > >>what the Squid limits are.
> > >>
> > >>USED HARDWARE:
> > >>Processor: P4 1.8GHz
> > >>Memory: 1 GB
> > >>Hardisk: 40 GB IDE 7200rpm
> > >>Controler: Serverworks Chipset
> > >>Ethernet card: Broadcom TG3
> > >
> > >>ACHIEVED PERFORMANCE:
> > >>Byte Hit Ratio: 13% (TOO LOW !!!)
>
> > Ow Mun Heng wrote: You want to save bandwidth or you want speed??
>
> On 02.12 13:13, Martin Marji Cermak wrote: Yes, I want to Save bandwidth.
>
> In such case you probably need: bigger cache (add new disk probably) lower
> - maximum_object_size cache_replacement_policy heap LFUDA
>
> explanations below
>
> > >>USED CONFIGURATION: maximum_object_size 51200 KB (SHOULD I MAKE IT
> > >>HIGHER ???)
> > >
> > >I made mine to cache up to 40MB only. If you really want to have more
> > >byte hit ratio, then by all means, up the max_obj_size.
> >
> > OK, now I have: maximum_object_size 200 MB
>
> I increased maximum_object_Size from 20MB (last time I verified what files
> were repeatedly fetched they were under 20 MB) to 32 MB and the byte hit
> ratio decreased.

Well, if he really wants to save on bandwidth and have the cache big
enough, I don't see why having a max obj size of 200MB to be not good.

Then again, it depends on usage.

>
> Yes, I work by an ISP where customers use to fetch very different files,
> that is expected. I don't know what situation you are in, but note that
> one 50MB file takes space of 50 1MB files and there is big probability
> that smaller files will be fetched more often.

True. One 50MB file = 50x hit ratio of 50 1MB file.

Thus, higher Byte_hit_ratio

>
> > >>cache_dir aufs /cache 25000 16 256 (one ide disk, see the spec above)
>
> > >This seems too low. I used 40GB of the 80GB drive
>
> > OK, I changed it to cache_dir aufs /cache 92000 16 256
>
> no no no, even if you have whole drive for the cache, you should note that
> there is some overhead in filesystems etc. I'm glad that I may use 30000
> kB (which is a bit less than 29GB) on 36GB hdd. You probably should use:

Proper usage is to use ~70-80% MAX of the physical HD space being
allocated for the cache.

--
Ow Mun Heng
Gentoo/Linux on D600 1.4Ghz 
Neuromancer 16:11:04 up 6:21, 6 users, 0.57, 0.53, 0.46