[filmscanners] RE: Slightly OT: Hard Drive Speed

["Austin Franklin" <darkroom@ix.netcom.com>]

> > The newer and larger 7200 rpm drives typically have a larger
> > cache than the
> > older drives, and this would provide a larger performance gain
> than going
> > from an Ultra ATA 66 to Ultra ATA 100.
>
> Do you believe a larger cache helps with large file reads and writes?  For
> reads it is no help, and for writes, it's really not much help either.  It
> helps for smaller file writes...for sure.  Imaging files are
> typically very
> large, and speed is mostly limited by drive media transfer rate.
>
> ------------
>
> The difference in performance between Ultra ATA 66 and Ultra ATA 100 will
> vary between make and model of drives of course, but generally, it's quite
> minimal. The biggest difference in drive performance would be as
> a result of
> the newer models incorporating newer technology and features to
> improve hard
> disk performance,

> of which a larger cache plays a significant role.

Cache only plays any role if the files are smaller than the cache size, for
a write, and no role for a read, unless it's a RAID system.

> There
> aren't that many drives that could saturate an Ultra ATA 66
> interface, it's
> doubtful that bumping the theoretical transfer rate from Ultra 66
> to 100 and
> now to 133 will make much of a difference in throughput.

That is STRICTLY because of the media transfer rate, which is strongly based
on drive RPM.

> IDE drives keep getting faster, but the next quantum leap in HD
> performance
> may come as a result of the new serial interface.

The ONLY way current interface hard drives will get faster is by increasing
the media transfer rate...the rate that data can be read from and written to
the actual platter.  That is the current bottleneck in hard drive
architecture.  It is not the interface or the cache.  As I said, larger
caches mean nothing for reads, unless in a RAID system, and nothing
"significant" for a write for large files.  Again, it's strictly the media
transfer rate that has been improving over the years and makes for faster
hard disks.

...you still haven't answered my questions as to why you believe caches help
with image files, and what, specifically, the two drives you were comparing
were that had this 5x price differential.

Quantum 18G Ultra SCSI 7200 - $64
IBM 20G UDMA 7200 - $65

Check on www.pricewatch.com and you'll see that the prices are comparable
for COMPARABLE drives.  If you are comparing a 10k RPM SCSI drive with a
5.4k RPM, that's hardly a fair comparison.

Austin

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