Ok, time to veer this another direction (grin).

When RAID controllers are writing to the drives, are they
doing it in any standard fashion?  For example, if I buy a 
Mylex Acceleraid 150, and in five years it burns out,
will I need a Mylex Acceleraid 150 to read the data from
the drives?

Kent


Nick.T.Reinking at supervalu.com wrote:
> 
> Ahh, coolness.
> 
> In response to CPU Util, recently, IDE drives have had
> lower CPU util than SCSI (because of DMA).  It's mostly
> a driver issue, and the amount of CPU util is just a few
> percent, anyways.
> 
> However, software RAID will seriously hurt your CPU Util.
> The Escalade does the IDE RAID in hardware, so it only
> uses a few percent of CPU to do your RAIDness.
> 
> Nick
> 
> jasonj at innominatus.com, on 10/17/2000 02:37:10 PM
> To: tclug-list at mn-linux.org @ PMDF
> cc:
> Subject: Re: [TCLUG:22757] Raid and other storage stories
> 
> No, RAID 10 is striped parity information. Similar to RAID 5 that has a
> dedicated
> drive for parity informaiton. RAID 10 stripes the parity across all drives.  If
> one
> drive fails, the replacement drive is rebuilt with the parity info from the
> other
> drives. I think there is more performance than RAID 5.
> 0+1 is not 10. 0+1 is 2 drives striped, and 2 more mirroring the stripe.
> 
> Nick.T.Reinking at supervalu.com wrote:
> 
> > RAID 10 == RAID 0+1.
> >
> > The difference is that the Escalade does it in hardware,
> > whereas the FastTrack and HighPoint do it in software.
> >
> > Nick
> >
> > jasonj at innominatus.com, on 10/17/2000 01:53:33 PM
> > To: tclug-list at mn-linux.org @ PMDF
> > cc:
> > Subject: Re: [TCLUG:22757] Raid and other storage stories
> >
> > Escalada 6xxx does RAID 0, 1, and 10
> >
> > Fasttrak does 0, 1, and 0+1
> > Highpoint does 0, 1, and 0+1
> >
> > Nick.T.Reinking at supervalu.com wrote:
> >
> > > Try www.elinux.com or www.thelinuxstore.com.
> > >
> > > Also, you don't need ATA/100 at all with just one device.
> > >
> > > As cool and fast as those 75GXPs are, they're not going to top
> > > more than 40MB/sec.  Easily under 66MB/sec.
> > >
> > > AFAIK, you can do all the weird partitioning that you could do
> > > with a real SCSI RAID controller.  The only bad thing about them
> > > is that they don't support RAID 5.  Only RAID 0,1, and 0+1, and
> > > JBOD, I think.
> > >
> > > Nick Reinking
> > >
> > > dopp at acm.cs.umn.edu, on 10/17/2000 01:14:41 PM
> > > To: tclug-list at mn-linux.org @ PMDF
> > > cc:
> > > Subject: Re: [TCLUG:22757] Raid and other storage stories
> > >
> > > On Tue, Oct 17, 2000 at 12:54:46PM -0500, Nick.T.Reinking at supervalu.com
> wrote:
> > > > The Escalade 6xxx series support ATA/66.
> > >
> > > Well, maybe they have an ATA/100 version planned...
> > >
> > > >
> > > > They're really cool...
> > >
> > > They look cool...
> > >
> > > >
> > > > 2-8 channels, 1 device/channel (which is why ATA/66 is
> > > > plenty good).  It's completely internal.
> > >
> > > Internal is good.  I have a full tower, so I'll have the room.
> > >
> > > >
> > > > The 3ware driver makes any RAIDed drives look like a single
> > > > SCSI drive.
> > > >
> > > > Furthermore, the 3ware supports other cool things such as
> > > > command queueing, etc.  Plus, they have an onboard co-processor.
> > > > (same one most SCSI RAID cards have).
> > >
> > > How about logical partitioning?  Does the Escalade allow me to make, say, 4
> > > drives into a single logical drive and then partition that logical drive
> > > into say, 3 logical partitions which all appear as seperate drives to my
> > > machine?
> > >
> > > The reason I ask is because I was thinking about the following setup:
> > >
> > > 4 30GB ATA/100 Deskstars
> > > 1 logical drive
> > > 2 logical partitions
> > >
> > > I suppose I could just take the 1 logical drive and partition it through
> > > the OS, but if the controller handles it for me, it's that much nicer.
> > >
> > > >
> > > > The FastTrack card is both poorly supported, plus it doesn't
> > > > have a co-processor.  All it does for you is make your RAID
> > > > drives look like one drive.  It's still all software otherwise.
> > >
> > > Ah, thanks for the heads-up.
> > >
> > > >
> > > > >From what I've heard, these cards are pretty amazingly fast.
> > > > IDE is faster than SCSI for one device, since the command
> > > > set is much smaller (and faster).  Since there is only one device/channel
> > > > on this controller... well, it's pretty amazing.  Plus, it has an
> > > > Alan Cox approved open source driver in 2.2.15+.
> > > >
> > >
> > > Eenteresteeng... I'll have to give it a try.  Where do you suggest I get
> > > one of these controllers?  It looks like one can only buy them through
> > > offical 3ware resellers.
> > >
> > > Gabe
> > > --
> > >
> >
> --------------------------------------------------------------------------------
> > > Gabe Turner                                    |           X-President,
> > > UNIX Systems Administrator,                    | Assoc. for Computing
> > Machinery
> > > U of M Supercomputing Institute for            |    Univerisity of Minnesota
> > > Digital Simulation and Advanced Computation    |       dopp at acm.cs.umn.edu
> > >
> > > "Dear Dr. Stupid: Why do I have to go to school?" -- Announcer
> > > "Your parents are aliens!!  While you're at school, they shed their
> > >  human skins and breathe dryer lint!!"
> > >                                         - Dr. Stupid in "Ask Dr. Stupid"
> > >
> >
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-- 
Kent Schumacher

Structural Wood Corporation
4000 Labore Rd.
St. Paul, MN 55110

Phone: (651) 426-8111
Fax: (651) 426-6859
e-mail: kent at structural-wood.com

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