Re: DASD Performance

DASD Arms are still important. For instance, a dual-processor S20 with
RAID-5 must have at least 9 arms (read 9 DASD units) for LIGHT disk
load. If the same machine has Mixed to Heavy load it requires at LEAST
27 arms for adequate performance.  
-- 
Richard Rosenbluth
Rose Information Management Co.
mailto:rose400@pacbell.net
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> Dean Asmussen wrote:
> >I heard a _NASTY_ rumor last week, and wanted to confirm it here.  While 
>we've
> >had our tuning differences here in the past (I prefer manual tuning, others
> >prefer QPFRADJ set on), one thing we've always agreed upon is that the number
> >of disc arms is important.  Now I hear that arms are irrelevant on the new
> >SCSI-based boxes, because the SCSI architecture will only access one drive at
> >a time.  Is this true?  If so, how does one tune hardware under this new
> >paradigm?  All the books still talk about arms!!!
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