Re: Reducing HDD writing affect on whole system.
Am Sonntag, 16. Oktober 2011 schrieb Sthu Deus:
> Thank You for Your time and answer, Martin:
> >Huh? Well compared to SSD they are dog slow with small size random
> >read/write operations - typical refered to as IOPS - but I cannot
> >confirm that they are slower than PATA drives. They might not be that
> >much faster, but thats IMHO more a question of the physical attributes
> >of their mechanics.
>
> I agree. That's what I want to solve. So for farther discussion let's
> just have as initial data: SATA HDD lacks performance on a system and
> we are looking for solutions. - Just to avoid the comparison of the
> standards.
>
> >As far as I have seen and measured, SATA drivers in the kernel operate
> >almost at hardware speeds. libata is a quite mature and performant
> >driver framewark as far as I have seen.
>
> How do measure? W/ hdparm?
hdparm -tT might give an initial figure. But I suggest it to run it at
least three times and look at how the values deviate, as the test time of
hdparm -tT is to short.
You might want to try dd with conv=fsync or oflag=direct a try as well. Be
careful not to overwrite your harddisk ;).
For more sophisticated test you can try to use fio with a simple workload.
For just copying a big file that would be a mixed read/write workload, but
you can start by testing read and write separately.
> >That said there might be exceptions with certain boards or
> >controllers. So if SATA is measurably slower on your machine than PATA
> >it might be an idea to replace the SATA controller or the board with
> >something sensible.
>
> It is not the case for now - what I said was long ago and I have no
> more those machines. Why I said that is just to share my experience w/
> S/P -ATA HDDs performance in Linux. And that's it.
Ok, then we disregard it unless proved otherwise.
> >Exactly. Please start with supplying the information I requested in
> >the other mail.
>
> OK. Please check it.
Did so. See there.
Ciao,
--
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7
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