Re: DASD Performance

[therrin@xxxxxxxxx (Terry Herrin)]

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!!!

When we configured the S20 two-way system we will be purchasing
shortly, arms were definitely a concern to IBM.  We were considering
going with the new 17Mb discs until IBM told us we needed to use 8Mb
discs so we would have enough arms for performance.

Terry Herrin
therrin@isaac.net
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