Mr. Issa(*) wrote:
Ok mate the scenario is as follows:
Clients -->> Mikrotik Router -->Squid BOX
Traffic of port 80 is Natted on the MK router to the Squid Box.
Squid is installed on Debian lenny. Debian is running on an intel
SSR212MMC2 system with the following specs:
32GB of Rams
8Terra Hard Disk on a HW RAID controller each 4hds are RAID10 and
mounted as 2 cache directories
My opinion of RAID behind Squid is very poor. Avoid if at all possible.
HW RAID is claimed to be workable though, particularly as the price
range and quality goes up.
The RAID0 operations of striping are duplication of the object spread
Squid itself performs between its cache_dir. So all you really gain
there is a larger total disk (Squid don't care about that) and risk of
loosing the entire lot if any stripe platters die.
The RAID1 can provide backup against disk failure (Squid like that).
Thats about the only benefit there. Con is just whatever overheads the
RAID controller has for a LOT of writes.
cache1 & cache2
/dev/sdc1 1.8T 87G 1.7T 5% /cache1
/dev/sdd1 1.8T 87G 1.7T 5% /cache2
pr0xySRV:~# free -m
total used free shared buffers cached
Mem: 32242 32065 176 0 1361 7570
-/+ buffers/cache: 23133 9109
Swap: 1898 0 1897
squid conf:
cache_dir aufs /cache1 1335043 16 256
cache_dir aufs /cache2 1335043 16 256
cache_swap_low 90
cache_swap_high 95
>
cache_replacement_policy heap LRU
memory_replacement_policy heap LRU
The problem is as you can check the previously attached Graph .. the
Small tick at an hourly interval.... and the Problem started to appear
When we had 100GB of cache as a sum of both cache_dir
Everythign you say just above confirms for me that the 5% swap high/low
difference will be the problem.
* The default garbage collection is ... done hourly. It won't
completey halt requests going through, but will take up a relatively
large chunk of CPU walking the index scheduling stuff to be removed.
* the removals only get done deeply when cache_swap_low % of the cache
is full.
* when cache_swap_high % of the cache is reached things get extra
strict and use even more CPU doing removals.
Amos
--
Please be using
Current Stable Squid 2.7.STABLE7 or 3.0.STABLE24
Current Beta Squid 3.1.0.17
