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Re: filmscanners: RAID and scratch

At 09:22 PM 17/11/01 -0500, you wrote:
>on 11/17/01 7:51 PM, Charles Knox wrote:
>> In general, the RAID partition would be faster, but not by as much as you
>> might think, since it would also be creating more seeks on the primary
>> drive, thus slowing it down quite a bit.
>Forgot to ask about where the system and application should go. Lets say I
>have three disks, one of which is the RAID. I was thinking to use my
>smallest drive for my OS and applications (including PS), the RAID
>exclusively for images, and a third drive for a second system, misc. backup,
>and a partition for scratch. Is this the best way to allocate system,
>images, application, and scratch, across the three drives or should they be
>grouped differently?


Your RAID system will need to consist of TWO drives, preferably identical,
to achieve what you have in mind,  so you'd have a two-drive RAID 0 system,
plus a stand-alone drive.

How you allocate the RAID system will depend largely on what gives your
disks the most work -- something you'll probably find mostly by trial and

In general, if you have lots of RAM, you're handling really large images
and they're accessed frequently, the way you suggest would likely be best.

However, if RAID on Mac is like RAID on PC (probably is), your RAID system
will usually prefer to be the primary (boot) drive unless directly
supported in BIOS.

What you really need to do is work out which part of the operation will
benefit most from the extra disk speed (operations done once only, such as
boot-up or application loading, don't gain you much.)

I find it really doesn't seem to matter much, though. 

Since UDMA 100 arrived everything (including Windows glitches--) ) happens
faster than I can keep up with anyway.

Case in point -- just yesterday I had a problem with EasyCD Creator 5 (so
what's new...) and checked hard disk speeds to rule out one possibility.

The RAID system reported around 46 MB-sec -- the stand-alone drives came in
between 17.4 for an ATA66 and 26-odd for an ATA100 -- these were read
speeds, of course, no multi-tasking and varied by file size (smaller or
badly fragmented files are slower.)

In a word -- experiment (but do be sure you understand what it's all about



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