RAID compatability between different controllers.

[jtpryan]

I have an Intel 865Perl motherboard with SATA on board that supports
RAID 0 or 1. I want to put 2 160 SATA drives in using RAID 1. My
concern is if someday the MB goes and I put another one in with on
board RAID, or use say, an external Promise controller, will they
recognize the drives? I realize I may have to rebuild the mirror, but
will they at least see the drives as individual entities?

-Jim

 

[frodo]

I have an Intel 865Perl motherboard with SATA on board that supports
RAID 0 or 1. I want to put 2 160 SATA drives in using RAID 1. My
concern is if someday the MB goes and I put another one in with on
board RAID, or use say, an external Promise controller, will they
recognize the drives? I realize I may have to rebuild the mirror, but
will they at least see the drives as individual entities?
-Jim

A good question. The "safe" answer is NO, all bets are off. Sorry.

The typical way that a raid volumn is initially created is to run a
bios-based utility that defines the array. At that point the utility
ASSUMES the drives are raw and can be overwritten. So, any "good" data
left on the one surviving drive will be lost when the new array is
initialized. The "rebuild the mirror" feature works only when the array is
already defined and the controller discovers a fault on one of the
drives. [it does not compare the contents, ever; it mearly deals w/ any
faults reported by the drive.]

But, what MIGHT work is installing the remaining good drive as a
stand-alone drive on a spare connector; it MAY be recognized as a simple
drive, and you could then back it up to other media, than restore that to
the new array after it's built. [this only works for RAID 1, where the
disks all contain the same image; for raids where the file contents span
multiple drives it surely won't work.]

Since you are in the position of building a new system you might want to
take a bit of time and try it now; build the array using the 865
interface, partition it and install XP. Make sure it boots, but don't
install anything else or fuss any further. Then remove the drives and
connect just 1 to IDE1-Master and see if it'll boot from it. If so you
know that no hidden confiuration data written to the drive by the raid
controller affects normal operation. If all is fine you have at least
some piece of mind. If not then you know for sure it won't work! After
the experiment I'd deffinately start all over again when building up the
system, don't rely on that first XP install (just in case!).

Bottom line: you still need to make backups!

 

[jtpryan]

I have an Intel 865Perl motherboard with SATA on board that supports
RAID 0 or 1. I want to put 2 160 SATA drives in using RAID 1. My
concern is if someday the MB goes and I put another one in with on
board RAID, or use say, an external Promise controller, will they
recognize the drives? I realize I may have to rebuild the mirror, but
will they at least see the drives as individual entities?
-Jim

A good question. The "safe" answer is NO, all bets are off. Sorry.

The typical way that a raid volume is initially created is to run a
bios-based utility that defines the array. At that point the utility
ASSUMES the drives are raw and can be overwritten. So, any "good" data
left on the one surviving drive will be lost when the new array is
initialized. The "rebuild the mirror" feature works only when the array is
already defined and the controller discovers a fault on one of the
drives. [it does not compare the contents, ever; it merely deals w/ any
faults reported by the drive.]

But, what MIGHT work is installing the remaining good drive as a
stand-alone drive on a spare connector; it MAY be recognized as a simple
drive, and you could then back it up to other media, than restore that to
the new array after it's built. [this only works for RAID 1, where the
disks all contain the same image; for raids where the file contents span
multiple drives it surely won't work.]

Since you are in the position of building a new system you might want to
take a bit of time and try it now; build the array using the 865
interface, partition it and install XP. Make sure it boots, but don't
install anything else or fuss any further. Then remove the drives and
connect just 1 to IDE1-Master and see if it'll boot from it. If so you
know that no hidden configuration data written to the drive by the raid
controller affects normal operation. If all is fine you have at least
some piece of mind. If not then you know for sure it won't work! After
the experiment I'd definitely start all over again when building up the
system, don't rely on that first XP install (just in case!).

Bottom line: you still need to make backups!

Good points. Actually, I did do this once when I built my media
server. I had an old MB with RAID on board. Once I got it all set up
and running the way I wanted (of course), the smoke escaped from the MB
and it was gone.

So, I bought a new MB and a Promise controller and installed everything
but the second half of the mirror. I got it to boot, discover all the
new "stuff" on the new MB and got it running again. I then installed
the other half of the mirror and rebuilt it anew.

So, your advise is right on. But I just didn't know if I got lucky the
first time, which is why I asked. Anyway, I will do as you say,
experiment before going too far.

-Jim