Re: [squid-users] High load server Disk problem

Hi!

In my own personal opinion: your hard drive alone is not enough to
handle that much traffic (110MBytes/s, ~1Gbps). See, most SATA hard
drives (7200rpm) gives around 50~70MB/s *sequential* read speed, your
cache reads are *not* sequential, so, it will be slower. In my
opinion, you need something like a 8 drives RAID10 array, and/or use
faster disks (10k), or maybe 15k SAS disks.

Also, I would put a minimum object size for disk of 1M, and a maximum
object size of whatever you want (this depends on your network, but
usually ~150MB is enough to fit almost any upgrade download). And for
RAM, I would put a maximum object size of 1M, with no minimum. Thus,
keeping small files out of the disk cache.

Also, other questions: How many clients/connections are you handling?
what are your server's specifications? and how is the system load over
time? (maybe zabbix or any other monitoring system will let you know
your system load over time).

I hope this helps,

Ildefonso Camargo

On Tue, Aug 17, 2010 at 10:26 PM, Robert Pipca <robertpipca_at_gmail.com> wrote:
> Hi.
>
> I'm using squid on a high speed network (with 110M of http traffic).
>
> I'm using 2.7.STABLE7 with these cache_dir:
>
> cache_dir aufs /cache 756842 60 100
> cache_dir coss /cache/coss1 65520 max-size=1048575
> max-stripe-waste=32768 block-size=4096 membufs=15
> cache_dir coss /cache/coss2 65520 max-size=1048575
> max-stripe-waste=32768 block-size=4096 membufs=15
> cache_dir coss /cache/coss3 65520 max-size=1048575
> max-stripe-waste=32768 block-size=4096 membufs=15
>
> Everything works fine most of the day, but on peak hours, I got these:
>
> 2010/08/17 20:06:59| squidaio_queue_request: WARNING - Disk I/O overloading
> 2010/08/17 20:06:59| squidaio_queue_request: Queue Length:
> current=981, high=1488, low=321, duration=170
>
> After a while, I got a few of these, with "duration" increasing, until:
>
> 2010/08/17 20:23:09| squidaio_queue_request: WARNING - Disk I/O overloading
> 2010/08/17 20:23:09| squidaio_queue_request: Queue Length:
> current=558, high=2177, low=321, duration=531
>
> The web browsing started to get very slow, which is when the support
> team took squid down.
>
> All cache_dir are on a single sata-2 7200RPM 1TB hard drive.
>
> Is there a way to know which cache_dir is the problem and what I can
> so this doesn't happen?
>
> I tried using both 16 and 32 AIO threads, but didn't help.
>
> cache manager tells me that I have around 10 million objects:
>
> Average HTTP requests per minute since start: 18851.1
>
> Storage Swap size: 693535688 KB
> Storage Mem size: 30872 KB
> Mean Object Size: 64.50 KB
>
> Internal Data Structures:
> 10752896 StoreEntries
>    49 StoreEntries with MemObjects
>    26 Hot Object Cache Items
> 10752847 on-disk objects
>
> Please help!
>
> - Robert
>
Received on Wed Aug 18 2010 - 03:13:35 MDT