[CentOS] Re: Anaconda doesn't support raid10
Ross S. W. Walker
rwalker at medallion.com
Thu May 10 16:04:02 UTC 2007
> -----Original Message-----
> From: centos-bounces at centos.org
> [mailto:centos-bounces at centos.org] On Behalf Of Ruslan Sivak
> Sent: Thursday, May 10, 2007 1:43 AM
> To: CentOS mailing list
> Subject: Re: [CentOS] Re: Anaconda doesn't support raid10
>
> Feizhou wrote:
> > Ross S. W. Walker wrote:
> >> Hey look at me! I'm top-posting!!! Nanny-nanny-poo-poo
> >>
> >> Come get me Trolls!
> >
> > Please do not top post. :)
> >
> He was probably hinting at me for top posting.
> Unfortunately, sometimes
> I write from the blackberry, which only allows top posting.
> Take it up
> with RIM.
> >
> >> SATA drives typically do 60-70MBs, interleaved you
> >> should see 120-140MB/s on sequential. Random IO on SATA
> >> usually sucks too badly to even talk about...
> >
> > Eh? It cannot be worse than PATA drives now can it?
> > _______________________________________________
>
> Probably not, but is SATA really much worse then SCSI or SAS? I did
> some testing on a dell PE 2950 of 750GB SATA's vs SAS and
> SCSI drives,
> and the SATA drives seem to be faster at least at first
> glance. I don't
> have good numbers from the SCSI tests, but at least for
> sequantial, I'm
> getting a better speed off the SATAs.
SATA and SCSI/SAS should give comparable single work-load sequential
numbers, but most SCSI/SAS have better seek times so random IO will
be better on those. Also SCSI/SAS support tagged command queuing,
which allows multiple overlapping IOs so you will tend to see better
mixed workload performance compared to SATA (multi-user environment).
Having said that some of the new SATA models that support NCQ, the
SATA version of TCQ, and that use some of the same SCSI/SAS onboard
processing (Western Digital Raptors) can approach or equal SCSI/SAS
mixed load performance, but their price also approaches or equals
SCSI/SAS and their spindle speeds still do not top 10K so random
will not be as good.
-Ross
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