I'll jump in here.
Raid 0, striping, assigns half of the data to one
drive, the other half to the other drive. The writes
happen more or less simultaneuosly, so large file
operations happen in roughly half the time.
Raid 1 is, as you said, mirroring, where all data are
duplicated, so that if a drive fails, another exact
copy is ready to take over (after a command to 'break'
the mirror set).
Classically, Raid 5 has a single chain logically (IDE
is limited to 2 devices per chain, and the above have
both drives on one chain (channel)). The Adaptec RAID
card works somewhat differently and allows multiple
channels to behave as one. Raid 5 then can be thought
of as n number of disks with the data striped as in
Raid 0, but with parity error information saved along
with the data. The amount of redundant data used is
1/n, so the total amount of storage is (drive
capacity)*(n-1).
Raid 0+1 is an IDE only hybrod that allows you to use
both channels with two disks such that you get
mirroring of two striped disks.
I know of no motherboard based IDE Raid solutions that
are designed for high performance (Preben mentioned
that the host CPU does the drive I/O processing).
Apparently, the Adaptec IDE Raid PCI card handles
this. I have no experience with this card (though I
use Adaptec SCSI adapters exclusively). At work I have
a card similar to what Preben described. It is made by
3Ware (www.3ware.com), and is called the Escalade. I
can heartily recommend this card under Win2000, the
only OS I have used it with. It is available with
support for 2, 4, or 8 IDE drives. At this time, it
doesn't yet support the new ATA133, so I guess you'd
be limited to 8 of Maxtor's 100 gigabyte drives!
There are actually several other levels of RAID, but
they are mathematically undesirable as regards the
cost/benefit/performance tradeoffs. For performance,
striping offers the best value. But it also offers no
protection for your data, so is only desirable when
data safety is not mandatory. Otherwise, RAID 5 is the
best combination of safety and performance.
Pat
--- LAURIE SOLOMON <LAURIE@ADVANCENET.NET> wrote:
> Preben,
> Since you seem to be knowledgeable about IDE RAID
> matters, I wish to make
> use of your knowledge as a resource even if it is OT
> for this list. I
> recently bought an ABIT motherboard with RAID. The
> manual is not very clear
> as tot he difference between RAID 0 (striping) and
> what it does versus JBOD
> (spanning). I understand what RAID 1 (mirroring) is
> and how it works; but I
> really do not understand how RAID 0 works or what
> parallel operation of the
> two drives on the channel means and entails.
>
> While it may be different for third party RAID
> controllers, the manual for
> the RAID controller on the ABIT KG7-RAID motherboard
> says that you need 4
> drives to use RAID 0+1 and that the second pair
> duplicate the first pair.
> This appears to contradict your point concerning
> "You "pay" the equivalent
> of one drive i.e.. - in this case - 100 GB for the
> security of your data,
> but you end up with a 300 GB drive array." If I ma
> reading the manual
> correctly, at least on the ABIT RAID, you would have
> 200GB of original data
> storage and 200GB duplicate mirror backup protection
> under the RAID 0+1
> setup - especially if you follow their advice of
> using same size, make, and
> model of hard drive in the array. Could you comment
> on this in a way so as
> to add some clarification for a novice to RAID
> arrays.
>
>
> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf
> Of Preben Kristensen
> Sent: Sunday, November 11, 2001 5:35 AM
> To: filmscanners@halftone.co.uk
> Subject: Re: filmscanners: Best solution for HD and
> images
>
>
> IMO the best price/performance/data safety setup is
> IDE Raid 5. If you buy a
> Ide Raid 5 card (Adaptec makes a good one: 2400A,
> which sells for around 300
> US) you can then connect, say four IDE 100GB drives
> and get an array which
> is very fast AND fairly fault tolerant. You "pay"
> the equivalent of one
> drive ie. - in this case - 100 GB for the security
> of your data, but you end
> up with a 300 GB drive array and the ability to
> swap/hotswap a drive and
> rebuild the array should one of the drives fail.
>
> Also, by using UDMA/100 5400 instead of 7200 drives
> you get a slightly
> slover performance, but you gain by having much
> lower temperatures and much
> lower noise levels.
>
> Such a Raid 5 system would cost around 1300 US
> (depending where you buy) for
> 300 GB, but your data is much more secure than the
> simpler and cheaper Raid
> 0.
>
> Lastly, these stand alone Raid cards - unlike raid
> solutions on
> motherbords - have their own processors on board
> which takes over all the
> hard work, freeing up your system processor.
>
> Greetings Preben
>
>
> ----- Original Message -----
> From: "James Grove" <jpgrove@blueyonder.co.uk>
> To: <filmscanners@halftone.co.uk>
> Sent: Sunday, November 11, 2001 9:46 AM
> Subject: RE: filmscanners: Best solution for HD and
> images
>
>
> > I have just ordered a 60 Gig Maxtor ATA 100 drive
> (ATA 133 is also
> > available) I have done this because it is far
> cheaper than buying
> > another 36 gig drive to go on my U160 SCSI
> channel. I can get the Maxtor
> > drives for around 60 UK pounds, which means I
> could buy 4 of these IDE
> > drives for the same price as a Quantum U160 36gig
> drive!
> >
> > One thing to remember about Ide if you decide to
> give the drive a
> > beasting is to cool it with a slim cooler.
> >
> > --
> > James Grove
> > james@jamesgrove.co.uk
> > www.jamesgrove.co.uk
> > www.mountain-photos.co.uk
> > ICQ 99737573
> >
> > -----Original Message-----
> > From: owner-filmscanners@halftone.co.uk
> > [mailto:owner-filmscanners@halftone.co.uk] On
> Behalf Of Ezio c/o TIN
> > Sent: 10 November 2001 21:18
> > To: filmscanners@halftone.co.uk
> > Subject: Re: filmscanners: Best solution for HD
> and images
> >
> >
> > I would recommend to buy a U-160 SCSI ... from
> e-bay ... I have just
> > done this to integrate the other 3 U-160 I have
> and I have bought for
> > 102US $ a 18GB IBM 10000 rpm brand new under
> warranty. A 36GB 10000rpm
> > also IBM U-160 is rated for 170 US $ ...
> >
> > Sincerely.
> >
> > Ezio
> >
> > www.lucenti.com e-photography site
> >
> >
> > ----- Original Message -----
> > From: "Andrea de Polo" <andrea@alinari.it>
> > To: <filmscanners@halftone.co.uk>
> > Sent: Saturday, November 10, 2001 4:53 PM
> > Subject: filmscanners: Best solution for HD and
> images
> >
> >
> > > Hello,
> > >
> > > I have a CreoScitex scanner with attached a,
> Apple G4 Silver 733 with
> > > OS
> > 9.2.1 and 1GB of ram; I noticed that the internal
> HD is a slow 5400rpm
> > UltraAta HD; question: since I work only with
> Photoshop and my images
> > are about 60mb in size and I just have to open and
> save them during the
> > day (we process about 200 images/day), I was
> wondering what is the best
> > and effective way to speed up my work: buy a scsi
> external HD 10.000rpm
> > (total cost about 650 UK pounds), OR buy an
> internal UltraAta 7200 rpm
> > (total cost about 250 UK pounds) ???
> > >
> > > Again, we just have to open, retouch and than
> save our 40mb images,
> > > but
> > currently I am noticing that is taking a bit to
> access the HD.
> > >
> > > Thanks to give me your best solution for
> time/money issue. Andrea
> > > --
> > > ------------------------------------------------
> > > Fratelli Alinari Photo Archives and Museum
> > >
> > > The world's oldest picture library
> > > tel: +39-055-2395201
> > > gsm: +39-347-4883223
> > > fax: +39-055-2382857
> > > ------------------------------------------------
> > >
> >
> >
> >
>
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