Re: What is Ultra SCSI 320 like?

"Michael Baeuerle" <michael.baeuerle@xxxxxxxx> wrote in message news:n50op4-c7d.ln1@xxxxxxxxxxxxxxxxxxx
Folkert Rienstra wrote:
Michael Baeuerle wrote:

You can use striping ("RAID0") to increase the transferrate.

But you don't get a faster access time by using multiple disks.

Yes you do, with RAID1.

In theory, if you manually control the head positions and/or know the
spindle angles.

No, just by reading both drives as if they were striped, alternating IO.

A common RAID1 solution with 2 disks and no such capabilities

that use both disks for reading (to increase the transferrate)
have nearly the same head positions on both disks all the time.

Not if the access pattern is random (where access time matters) and
IOs are alternated between drives.

The angle of the spindles is unknown, therefore the controller don't
know which disk is better accessed first and the average access
times should be the same as for a single disk.

Not if they use them as if they were striped and the access pattern is
random. IOs are alternated between the drives so that access time is
'suffered' in parallel, rather than in series.



Micha
.

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