RAID 1 - where is configuration information stored?

Hello peeps,

Hope somone can help me in clearing up some concepts of software based RAID1.

Prerequisites

SIS966L southbridge - Support RAID 0/1/JBOD
2 x 160GB Maxtor SATA Hardrives
Windows XP

Now....

My first question is

What determines which drive is the 'master' drive in the array?

I refer to 'master' as the drive that will 'mirror' to the other hard drive.

My understanding is that one of the drives will be the 'live' drive which will send data to the other hard drive.

Does the 'master' hard drive hold initial boot configuration different from other drive?

The reason I am asking these questions, is because I have a problem that if the drives are disconnected from the array and an attempt is made to boot up from each of the drives independantly, one of the drives boots to windows fine will the other drive gives the message 'operating system not found'

I have given the commands fixboot and fixmbr, but still cannot get this drive to boot windows, even thought the OS is intact.

So I think my understanding is flawed of how RAID 1 works and hopes someone can help me in correcting any misconceptions I may have.

Thats about it, hope someone can help...

:)

This should not happen. There should be no "master" drive.
When you set up a mirror though, it should give you the option which drive to copy onto which drive, or presume drives are identical. If the latter, then any sector not written is actually not identical on both drives (but this should not matter for data retrieval, since unwritten sectors would not contain valid data anyway).

I remember someone else had a similar problem - the second drive would not boot. The only logical thing is a cable issue that wrote the wrong data to the drive boot sector, not anything else.

it could also be possible the controller does not write to the same locations on both drives, but does have a master drive as you say. The master drive would then be seen as a regular drive, while the second one would have RAID sectors, and that is what the BIOS sees.

Quote:

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Originally Posted by alfaunits

This should not happen. There should be no "master" drive.
When you set up a mirror though, it should give you the option which drive to copy onto which drive, or presume drives are identical. If the latter, then any sector not written is actually not identical on both drives (but this should not matter for data retrieval, since unwritten sectors would not contain valid data anyway).

I remember someone else had a similar problem - the second drive would not boot. The only logical thing is a cable issue that wrote the wrong data to the drive boot sector, not anything else.

it could also be possible the controller does not write to the same locations on both drives, but does have a master drive as you say. The master drive would then be seen as a regular drive, while the second one would have RAID sectors, and that is what the BIOS sees.

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Thanks for your response alfaunits,

What you explained clearly helps me in that the things you have said and suggested are similar to things I had also thought about.

Considering the position I am currently in, by what means could I create a means in which the non booting drive will boot?

My thought process from what I have read at wikipedia and on the adaptec website leads me to believe that I need to recreate the software layer that sits above the (generally block-based) disk device drivers and provides an abstraction layer between the logical drives (RAIDs) and physical drives

I think it is this abstrat layer that is corrupt or missing that needs to be fixed, re-created, before the data is passed over to the OS's kernal.

Id like to hear your views if this is correct or not, and if correct, if you have any idea on how one can go about fixing the boot problem.

Look forward to hearing your thoughts.

:)

Quote:

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Originally Posted by mongoled

The reason I am asking these questions, is because I have a problem that if the drives are disconnected from the array and an attempt is made to boot up from each of the drives independantly, one of the drives boots to windows fine will the other drive gives the message 'operating system not found'

I have given the commands fixboot and fixmbr, but still cannot get this drive to boot windows, even thought the OS is intact.

So I think my understanding is flawed of how RAID 1 works and hopes someone can help me in correcting any misconceptions I may have.

Thats about it, hope someone can help...

:)

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I'm a little bit fuzzy on the software RAID implementation.

As I understand it, Windows RAID mirroring will create a clone of the disk but to your BIOS/Controller it will still seem like two independent disks.

Have you tried Flipping the SATA connectors around or manually (changing the setting in BIOS) changing to boot the other disk first?

BIOS probably wouldn't even bother trying to boot from the 2nd disk otherwise regardless what you did in windows.

I think he used onboard RAID - SIS966L

Oh sorry. In that case you should have been able to just yank one drive out np and booted from the other