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

Ow Mun Heng 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 !!!)
>
> You want to save bandwidth or you want speed??

Yes, I want to Save bandwidth.

>>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

>>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

>>cache_mem 8 MB
> 200 MB. More being cached to memory. Faster retrieval.
Thank you, nice. I just hope it does not start swaping :-)

>>The Squid is configured as a transparet proxy, so:
>>httpd_accel_uses_host_header on
>>httpd_accel_with_proxy OFF (yes, transparent)
>>httpd_accel_port 80
>>httpd_accel_host virtual
>
>
> Say.. do you have any experience running a load balanced squid? I'm
> wondering, since it's transparent, what happens if Squid Goes down? (for
> X Reasons?) What happens to your ADSL users? (in the thousands??)
I am in a testing phase, trying to find out what can just one squid
handle - what are its limits. Then I will install a little Squid farm.

If Squid goes down, it drops all established connections. So, I am
supposed to have my Squid in a good shape :-), stable and running
without stopping/crashing.
The "thousands" means approx. 3500 users at the moment.

> Are you logging a lot of things? If you are, your IDE disk may not be
> able to sustain the throughput.
Yes, you are righ, I was logging quite a lot. I modified the debug
module a bit (I can set a debug level for each module, e.g.:
   debug_options ALL,1;14,2;99,4
) so now I log only info I need

And another interesting thing:

My median Byte Hit Ratio has reached 17% (200 MB max file, 95 GB cache).
So I drecompiled squid with --enable-removal-policies and set:
   cache_replacement_policy heap LFUDA
It looks I can gain a couple of percent (LFUDA should have a bit better
Byte Hit Ratio than lfu).

I will report some stats to the list, when I have more info (after I run
squid in this configuration for more days).

Have a nice day,
Marji
Received on Wed Dec 01 2004 - 22:13:19 MST