switching motherboards and RAID0 striping


Y

Yousuf Khan

Let's say someone has one type of motherboard, and they've got a
built-in RAID controller on it, which they're using in RAID 0 mode
(striping). Then later due to some reason or another they need to change
out the motherboard, due to an upgrade or a failure or whatever. Will
getting another motherboard with a built-in (or even an add-in card)
RAID controller feature work with the old setup? Do you have to keep the
chipset brands the same (eg. Promise vs. Adaptec, etc.)?

Actually this question also applies to RAID 1 configs (mirroring).

Yousuf Khan
 
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A

Ar Q

Yousuf Khan said:
Let's say someone has one type of motherboard, and they've got a
built-in RAID controller on it, which they're using in RAID 0 mode
(striping). Then later due to some reason or another they need to change
out the motherboard, due to an upgrade or a failure or whatever. Will
getting another motherboard with a built-in (or even an add-in card)
RAID controller feature work with the old setup? Do you have to keep the
chipset brands the same (eg. Promise vs. Adaptec, etc.)?

Actually this question also applies to RAID 1 configs (mirroring).

Yousuf Khan
I have seen the discussion here before. You should Google the topic. Anyway,
the conclusion is that not only you need the same brand, you need the same
model. You probably should buy the same model of mobo from EBay.
 
D

dg

Yousuf Khan said:
Let's say someone has one type of motherboard, and they've got a
built-in RAID controller on it, which they're using in RAID 0 mode
(striping). Then later due to some reason or another they need to change
out the motherboard, due to an upgrade or a failure or whatever. Will
getting another motherboard with a built-in (or even an add-in card)
RAID controller feature work with the old setup? Do you have to keep the
chipset brands the same (eg. Promise vs. Adaptec, etc.)?

Actually this question also applies to RAID 1 configs (mirroring).
Since you are talking specifically about RAID 1, I would imagine you would
be able to do it easily. I wouldn't think (but I could be wrong) that a
raid 1 array would be made up of normal looking disks, you know-nothing
special added by the raid card. Maybe somebody here will specifically know
that because I am guessing that the data wouldn't be written in any strange
format, its just like a SCSI card that has some brains enough to write to 2
drives instead of 1 and lookout for errors on 1 (I am waiting for somebody
to slam me on that....). If it is your boot drive, you are pretty much
roped into some tinkering anyway having to adapt the current OS
configuration to the new hardware without just rebuilding and copying over
any data. Figure you have 2 chances anyway, once you shut down the machine
and dismantle the drives, you have 2 identical drives full of good data.
Its backed up anyway right?

As to raid 0, there are software tools that can analyze and recover data
from arrays without original hardware. I believe they have been discussed
in the past here. If you were to do that, you would need a lot of free
space somewhere to hold the files. Or just buy new disks and configure an
array on the new hardware then copy over the data. That option might be
nice just to save yourself a possibly huge headache and loss of sleep and
money.

--Dan
 
G

Gary L.

Yousuf said:
Let's say someone has one type of motherboard, and they've got a
built-in RAID controller on it, which they're using in RAID 0 mode
(striping). Then later due to some reason or another they need to change
out the motherboard, due to an upgrade or a failure or whatever. Will
getting another motherboard with a built-in (or even an add-in card)
RAID controller feature work with the old setup? Do you have to keep the
chipset brands the same (eg. Promise vs. Adaptec, etc.)?

Actually this question also applies to RAID 1 configs (mirroring).

Yousuf Khan
The answer is different for different types of RAID:

RAID 0: A change in the RAID controller will normally result in the loss
of the array. You need the same controller to be able access the array.
That means the identical controller chip and possibly the same
BIOS/firmware for the controller. There may be exceptions where a
different controller from the same manufacturer will see the array, but
I wouldn't count on it. With different motherboards using built-in RAID
controllers, it is likely that the array will not be accessible with a
different model or brand of board.

RAID 1: Both disks have identical data and can operate independently
from each other. So if one disk malfunctions, all data is preserved. You
can take a good disk and use it with virtually any controller (RAID or
conventional) and have full access to the data. RAID 1 controllers do
write data to the the disks defining the arrays. When you switch
controllers, the new controller may not be able to read this data and
thus will not see the disks as an array. It will report the array as
"depreciated." But it is trivial to restore the array simply be defining
a new array within the controller and then allowing the controller to
duplicate the data on the "good" disk onto the "new" disk.
 
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G

George Macdonald

Let's say someone has one type of motherboard, and they've got a
built-in RAID controller on it, which they're using in RAID 0 mode
(striping). Then later due to some reason or another they need to change
out the motherboard, due to an upgrade or a failure or whatever. Will
getting another motherboard with a built-in (or even an add-in card)
RAID controller feature work with the old setup? Do you have to keep the
chipset brands the same (eg. Promise vs. Adaptec, etc.)?

Actually this question also applies to RAID 1 configs (mirroring).
Most of the RAID-1 docs tell you to install the OS first on a single drive
with normal mbrd IDE controller... then load the RAID drivers into the OS,
then shutdown and transfer the drives to the RAID controller and build the
RAID array from the controller's BIOS or even in the OS itself using the
RAID drivers. So unless the docs say different, the disk sector layouts
have to be the same as any other IDE controller. If you switch RAID
controllers, which is essentially what your saying, the worst you have to
do is rebuild the mirror. If the new RAID controller is by the same mfr
you might get lucky and not have to do anything except load slightly
different drivers before the switch.

Of course the other nice thing about RAID-1 is that you have a mirror
anyway - you can power one off for the switch and even make an extra spare.
I've done this with our Promise Superswaps and it's always nice to know you
have another "backup". I've also used BootitNG's Partition Management to
repartition our server with just one drive connected to the Promise
controller, then checked the boot and startup works before turning the 2nd
drive on.

For RAID-0, there may be some RAID management info transfer/conversion
utilities kicking around, possibly intra-manufacturer... maybe even cross
manufacturer, but I've never looked since I wouldn't touch RAID-0 for a
bootable drive anyway. I think I'd recommend getting a copy of Backup MyPC
from NewEgg for $38. and backing up to DVD+R before diving in.
 

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