On Thu, Dec 11, 2008 at 3:51 AM, Pasi Kärkkäinen <pasik AT iki DOT fi> wrote:
> On Wed, Dec 10, 2008 at 04:38:58PM -0600, Lukasz Szybalski wrote:
>> On Wed, Dec 10, 2008 at 4:06 PM, John Drescher <drescherjm AT gmail DOT com>
>> wrote:
>> > On Wed, Dec 10, 2008 at 4:10 PM, Lukasz Szybalski <szybalski AT gmail DOT
>> > com> wrote:
>> >> Hello,
>> >> My bacula server is pretty busy, and I notice that at times the IOwait
>> >> reaches 40%.
>> >>
>> >> Currently I use: top, free, iostat -k 5 /dev/md5
>> >>
>> >> Are there any tools/commands on linux that can tell me what is the
>> >> status of Input output. I would like to know:
>> >> - How much IO are my hard drives capable of?
>> >> - What is an average? max? min?
>> >> - Is IO a bottleneck on my performance?
>> >> - Monitoring tool names and exact commands would be appriciated.
>> >>
>> >> Sorry to bring these questions here but I don't know any other list
>> >> that would have the technical people that have experience and are
>> >> knowledgeable on the topic.
>> >>
>> >
>> > Is this a software raid 5 or 6?
>>
>> Software raid5 using mdadm
>>
>
> What kind of drives? how many of them?
>
> Single SATA 7200 rpm drive is capable of around 100-150 random IOs per
> second..
>
> You can check http://www.storagereview.com and go to "Performance Database"
> and select for example "IOMeter File Server - 128 I/O" and click "Sort" to
> see some results..
>
> SSD drives seem to beat the crap out of SAS and especially SATA drives:)
>
> 15k rpm U320 SCSI drives seem to be over 400 IOs per second..
> a lot faster than SATA disks.
>
> Anyway, the point was that even when a single SATA drive might have a nice
> sequential throughput, it won't do very well with random IOs.. If you're
> running multiple backup jobs at the same time you're pretty much having
> random IO patterns..
>
> Try benchmarking your md-raid-array and see how much IOs you can get out
> from it with random IO patterns? Try for example with LTP disktest.
>
> With LTP disktest you can try different IO sizes, different amount of threads,
> different read/write ratios etc..
So one way is to benchmark disks (4x 500GB WD raid5 ) . Is LTP
disktest the name of the software? Is it part of linux already?
How can I measure or benchmark the tps (transfers per second?) does that matter?
How can I measure or benchmark the IO from the system vs application ?
does that matter?
Thanks,
Lucas
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