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On 5/18/01, Hale Landis <[EMAIL PROTECTED]> wrote:
> .......
>So let me ask a few questions here...
>
>Do you know the logical LBA to physical LBA mapping for a drive?
>Do you know the zone layout? Do you know if the drive does
>small seeks faster than a head switch (most do!)? Do you
>realize that with write caching on all write commands have
>virtually zero "command overhead"? Do you realize that many
>drives can execute 5, 10, maybe a 100 commands all in hardware
>without the drive's firmware getting involved? Do you know that
>many drives will recognize the seek and read/write patterns of
>the most popular "performance measurement" software and adjust
>their caching operations so they look better while running that
>test? If you issue a bunch of seek commands without reading or
>writing data do you know if the drive is really doing the seek
>you think it should? Do you know if it is doing any seek at all?
>It might not even be spinning while you think you are doing those
>seek commands!
>
>I'm done for now... Someone else's turn!
Hale,
Very good points. However, you left out my favorite.... "Do you know if
the drive was making any retries ?" Some error conditions take a very
long time to recover and do not report any error.
Regards,
Harlan
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