Question: Disk Mirroring preceding RAID?

From: Geoff Roberts <>
Date: Sun Dec 10 19:41:54 2000

----- Original Message -----
From: "Richard Erlacher" <>
To: <>
Sent: Tuesday, December 05, 2000 11:37 AM
Subject: Re: Question: Disk Mirroring preceding RAID?

> Back in '90. I tried the Novell NETWARE approach to mirroring, but
> unable to make it work. That was due to the fact that the ADAPTEC
> controller I was using didn't really work correctly at the alternate
> with the driver they provided for that purpose.

Oh? Interesting. We have (somewhere) a Netware 3.11 server that is
disk mirroring with 2 Adaptec controllers.

The above is on-topic, that 486DX2-66 EISA server is now 10 yrs old hi,
and when it retires (probably next year)
I will be giving it a good home, along with its cabling, tape drive,
UPS, Deskjet 500 and dozen or so diskless workstations, so my kids can
play dos and win3.x based games, on their own personal Novell network,

Never had a problem with that, or with a later model server and NW4.11
mirroring, also with adaptec's - 2940UW's IIRC.

> I quickly abandoned it, in
> favor of the software RAID offered by NT.

Yeah, that part of NT seems ok as well. Ran that on some NT 3.51
systems we had here, but we
recovered our sanity and they went.

> It's theoretically quite solid, but I've never used it myself. The NT
> (software) approach seems more solid. RAID is always done in software
> greater or lesser extent. The RISC processors commonly used on
> "RAID-5-capable" controllers is really the same thing as it really
> matter who runs the software.

Yes, and there is a difference in sophistication. All RAID controllers
were not created equal.

Our current NW4.11 box is an NEC Express 130SA, dual P2-400's.
It has a mainboard embedded Mylex DAC960PJ Raid Controller, and it's
very good indeed.
We have 4 x 8.9Gb drives configured as RAID Level 5, so we have about
24Gb useable.
Drive failure is transparent to the O/S, and we have been able to reboot
the system with a dead drive,
hot swap remove/replace it 5 or 6 times, eventually replace it with
anonther drive, and have the raid controller
rebuild the drive in background, without any significant slowdown, and
no impact on data integrity at all, and no need
to reboot, reconfigure whatever. "It just works." I like it.....:^)

> Unfortunately, under NT4, there were problems
> with inter-process communication before SP3. That would make anybody
> suspicious. My NT server was emulating the NETWARE server, yet had
> advantage of the software compression offered by NT and the built-in
> (not the best imaginable, but the best there is <sigh>)


> AND it emulates the
> NETWARE server so I can use it from DOS workstations.

Is this the NT - Novell Gateway? Tried that, seemed to work ok, but
couldn't really see the point.


Geoff Roberts
Computer Systems Manager
Saint Mark's College
Port Pirie,
South Australia
ICQ: 1970476
Received on Sun Dec 10 2000 - 19:41:54 GMT

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