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RE: filmscanners: RAID and scratch

OK!  That is what I originally though I had read but the new statement made
me think that I had confused you with another poster with regards to the
equipment list and set up.

I would make a few changes to what you proposed.  I would keep drive A as
you have it.  I would put both the data and image files and the scratch disk
on drive B (your RAID 0 array), partitioning it 2/3 to 3/4 for data and
images and 1/4 to 1/3 for a scratch disk.  I would use the third disk by
partitioning it into two partitions (one partition of 1GB for your Windows
Swap file and one partition of 59GB for backup.  My reasoning is as follows:
The RAID array's performance will be better than either disk A or B.  Since
you will be making frequent writes and reads from the image and data files
as well as from your Photoshop scratch file, you would want them to be on
your fastest drive arrangement.  Since the drive C is faster than drive A,
you would want to put your Windows Swap file there rather than on your
slowest drive since that swap file is accessed frequently also by both
Photoshop and Windows as well as by your other programs under windows for
virtual memory.  However, in so far as the accessing of the Windows Swap
file is not as intensive as that of the Photoshop scratch file when they are
being used comparatively speaking, I do not think there is a strong
justification for locating it on the RAID array.

Hope that helps in giving you some ideas and suggestions.  I am also
assuming that you will be using drive C to do manual backups of selected
data files and will not attempt to use it to automatically mirror the RAID 0
or to backup all your data on the RAID array. While it may or may not be
possible to use it in a RAID 1 function, I think it would slow down the
whole RAID operation causing you to lose the performance benefits of the
RAID 1 - let alone run out of storage room as your RAID 0 Array begins to
fill up with data.

-----Original Message-----
From: owner-filmscanners@halftone.co.uk
[mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Todd Flashner
Sent: Sunday, November 18, 2001 1:12 AM
To: filmscanners@halftone.co.uk
Subject: Re: filmscanners: RAID and scratch


I don't blame you for reading me as you did. I did understand that it takes
two drives for my RAID 0. I will have four drives. When Charles said that a
RAID behaves like a single drive, I shorthanded my description of it by
referring to it as a single drive. My fault.

Allow me to attempt to clarify. What I will have is A) 27GB drive, B) 60GB
RAID 0 (using two 60GB drives), C) another 60GB drive.

The 27GB drive is probably the slowest drive, and the other three 60GB
drives will all be the same make and model (IBM Deskstar IDE). So with that
info, what is the best location for OS, Photoshop, images, backup?

Using the alphabet scheme I used above to denote my volumes, my plan was:

A) OS, Photoshop, misc.
B) Images
C) Partition for scratch, partition for backup.

Does that seem like the best way to distribute: system, application, files,
and scratch - across these three volumes for max speed? I know it's best to
have my scratch on a separate drive from the application, but I don't know
if it's best to group the OS with the app; or the app with the files; or the
OS, app, and files all together...


> I am not sure you understand how a RAID array works.  To establish either
> RAID O or a RAID 1 you need two drives (both of the same size and model
> preferably) for either the striping or the mirroring array.  To do a RAID
> + 1, you would need preferably 4 drives of the same size and model,
> you might be able to get away with having the mirroring drive be a size
> equal to the two striped drives of RAID O.  In point of fact, you can have
> only drive that would not be in the RAID array and on a non RAID
> which you could use to house your OS, swap files, scratch files, and maybe
> program files in one partition or in separate partitions on it if you set
> a RAID array for your data, since the array would take two drives minimum.
> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Todd Flashner
> Sent: Saturday, November 17, 2001 8:23 PM
> To: filmscanners@halftone.co.uk
> Subject: Re: filmscanners: RAID and scratch
> 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.
> and a partition for scratch. Is this the best way to allocate system,
> images, application, and scratch, across the three drives or should they
> grouped differently?
> Todd


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