I, for one, am extremely interested in the RAID discussion and want it to
stay on the list. It might be technically off-topic, but is useful knowledge
for anyone comtemplating mass storage of images scanned from, uh,
FILMSCANNERS.
There are a lot of threads on this list that I'm not interested in. Rather
than being a topic-nazi, I am not too lazy to use the DELETE key. Try it.
Lloyd
----- Original Message -----
From: "Stuart Nixon" <sns@ermapper.com>
To: <filmscanners@halftone.co.uk>
Sent: Tuesday, November 13, 2001 10:30 AM
Subject: Can we please move the RAID discussion off-list? (was RE:
filmscanners: Best solution for HD and images)
> Can we PLEASE take this RAID discussion off-list?
>
> It is not directly related to scanners. And there is enough misinformation
> being thrown around here that it is just confusing everyone.
>
> There is plenty of reference information for RAID systems on the web and
> elsewhere; we don't need to clutter the list up with this IMHO.
>
> If people want reference information on RAID systems, such as the fact
> that RAID 0 is indeed less reliable than a single drive or RAID 1 or 5, I
> refer
> you to information such as:
>
>
> ty
>
>
>
> /A701.8.FTnotes_010312A.pdf
>
>
> Thanks
>
> Stuart
>
> p.s. I saw some Mac users were asking about IDE RAID systems.
> Have a look at the new IDE/SCSI RAID 5 boxes from Promise and others,
> which have IDE drives, and SCSI out.
>
> a%20Sheet.pdf
> A 8 x 100GB IDE drive system gives about 700GB of usable space. I like
> these
> external RAID boxes, because they are low cost, have hot swappable drives
> and power supplies, and plug straight into a Mac/PC/Unix SCSI controller.
>
>
> [Original message]
>
> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Austin Franklin
> Sent: Tuesday, 13 November 2001 10:53 PM
> To: filmscanners@halftone.co.uk
> Subject: RE: filmscanners: Best solution for HD and images
>
>
> > MTBF of a RAID-0 system (or dual cpu/memory where one unit CAN
> > NOT continue
> > without the other) will always be lower than a single drive unless the
> > standard deviation (they never quote SD) of the MTBF is zero.
>
> Well, if you take duty-cycle into account, which MTBF calculations do, you
> will actually get higher MTBF for RAID 0, simply because the main failure
is
> the servo actuator, and when it is only being used for half the
time...MTBF
> will increase.
>
> > The reality for MTBF of a RAID-0 will lie in between.
>
> But that means it doesn't change compared to a single drive...
>
> > Cummalative failure rate is a much more useful figure for us and
> > for a small
> > number of fairly reliable inter-dependant devices this is nearly
> > an additive
> > figure - but not quite.
>
> That I completely disagree with. It is absolutely NOT additive. In fact,
> as I pointed out above, you may get HIGHER reliability by using RAID 0
> simply because of duty cycle and the common failure mode, both of which
are
> a very important part of MTBF.
>
> > Seagate reckon about 3.41% (flat-line model) will fail during the first
5
> > years of use (assuming you only use it for 2400 hours a year [6
> > 1/2 hours a
> > day]) :
> >
> >
>
> If you read that article you referenced, when they talk about multiple
> disks, they are talking about multiple PLATTERS in a single disk, not
> drives, so you can't derive the numbers you did for multiple drives from
> that article. No where in that article did they discuss multiple drives.
>
>
>
