Raid 0 recover (nvraid on windows)
Posted: Sat Feb 19, 2011 6:38 pm
I'm trying to recover a 2 disk RAID 0 array after a MoBo failure.
I'm working from disk images and I *believe* the disks themselves to be in an OK state.
Each disk is 153.39Gb (164Gb on the label)
The RAID 0 volume is coming up as 306.77Gb
I know the disk order.
I don't know the stripe size.
I have followed the general instructions in the excellent "Finding RAID parameters" document on your website, but have got a bit confused towards the end where stripe size it determined.
I'm not sure if this is a problem, but there appears to be a FAT16(?) partition at the start of the first disk, so I was wondering if the second disk needs some offset or other as a result, so that is starts at the same place as the NTFS partition on disk #1? Or will this be handled automatically?
Anyway, I have mounted my two images: "Disk#1" and "Disk#2" and I know that they are in this order, so I believe I should only really need to look at "Disk #1" for all the general parameter info, since "Disk #2" is just going to be striped data... is this correct? (In any case I have not found an MBR on Disk#2...)
So, I have found an MBR in "Disk#1": Sector 0 "with 2048 sectors preceding the partition"
As I only have 2 disks the calculation for starting to look for the NTFS Boot Sector = 2048, and indeed that is where I find it!
The Boot Sector info is basically the same as in your example:
Bytes/sector = 512
Sectors/Cluster = 8
Logical Cluster# for $MFT = 786432
Now, looking for the MFT:
Calculation is: 786432*8/(N-1=1) = 6291456 / 1 = 6291456
I find the MFT record at sector: 6293504 which seems about right.
So far, so good.
Now, I get confused...
I can see the "File Record Number" of this first position... it is 00 00
If I skip forward 2 sectors, it changes to 01 00 (obviously the hex is inversed)
But, as I have neither 3 disks no parity in my case, I am lost at this point.
All the subsequent "2 sector skips forward" increment the File Record Number by 1, right up to FF 4E at sector 6405022 !
I'm sure this can't mean that my stripe size is 1K (2 sectors) can it ? That seems rather ludicrous...
Could someone point me in the right direction with this bit, and possibly tell me if I need to do anything else on Disk#2 or if it just has to be added to the Raid Set when it is defined.
At the moment I am going ahead with a full scan of the set, using the 64k stripe size, as this seems to be the NVRaid default ("Optimal"), and I can't think it would have been changed.
Any assistance much appreciated!
Thanks,
Puss.
I'm working from disk images and I *believe* the disks themselves to be in an OK state.
Each disk is 153.39Gb (164Gb on the label)
The RAID 0 volume is coming up as 306.77Gb
I know the disk order.
I don't know the stripe size.
I have followed the general instructions in the excellent "Finding RAID parameters" document on your website, but have got a bit confused towards the end where stripe size it determined.
I'm not sure if this is a problem, but there appears to be a FAT16(?) partition at the start of the first disk, so I was wondering if the second disk needs some offset or other as a result, so that is starts at the same place as the NTFS partition on disk #1? Or will this be handled automatically?
Anyway, I have mounted my two images: "Disk#1" and "Disk#2" and I know that they are in this order, so I believe I should only really need to look at "Disk #1" for all the general parameter info, since "Disk #2" is just going to be striped data... is this correct? (In any case I have not found an MBR on Disk#2...)
So, I have found an MBR in "Disk#1": Sector 0 "with 2048 sectors preceding the partition"
As I only have 2 disks the calculation for starting to look for the NTFS Boot Sector = 2048, and indeed that is where I find it!
The Boot Sector info is basically the same as in your example:
Bytes/sector = 512
Sectors/Cluster = 8
Logical Cluster# for $MFT = 786432
Now, looking for the MFT:
Calculation is: 786432*8/(N-1=1) = 6291456 / 1 = 6291456
I find the MFT record at sector: 6293504 which seems about right.
So far, so good.
Now, I get confused...
I can see the "File Record Number" of this first position... it is 00 00
If I skip forward 2 sectors, it changes to 01 00 (obviously the hex is inversed)
But, as I have neither 3 disks no parity in my case, I am lost at this point.
All the subsequent "2 sector skips forward" increment the File Record Number by 1, right up to FF 4E at sector 6405022 !
I'm sure this can't mean that my stripe size is 1K (2 sectors) can it ? That seems rather ludicrous...
Could someone point me in the right direction with this bit, and possibly tell me if I need to do anything else on Disk#2 or if it just has to be added to the Raid Set when it is defined.
At the moment I am going ahead with a full scan of the set, using the 64k stripe size, as this seems to be the NVRaid default ("Optimal"), and I can't think it would have been changed.
Any assistance much appreciated!
Thanks,
Puss.