-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@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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