RAID5 recovery on Macintosh - RAID parameters
Posted: Thu Sep 12, 2013 9:25 am
Hi all -
Couple weeks back I had what appeared to be a 2 disk failure on my RAID5 6 disk (2Tb each) set-up disk array on my PROMISE Pegasus R6 drive (connected to my Macmini via thunderbolt).
There does not appear to be mechanical failure of the drives, so I proceeded to attempt data recovery via imaging the drives and rebuilding the virtual array using R-Studio.
Each of the drives appear to have imaged OK (took 6 days overall).
Based on a previous system dump using the PROMIS disk util of the array when I was trying to debug it, I think (though I am not sure) of the following RAID parameters:
Disk Order: I'm prettys sure I have the order of the array correct (confirmed via serial number)
Stripe Size: 128 kb
Block Order: "Right asymmetric" is what was given in the subsystem info check (assume that is analogous to Right Asynchronous)
Offset: Unsure
I set of a virtual array with 6 rows, 128kb block size, right asynchronous, and 6 rows. Each image has an offset set to "0 sectors"
I then begun a scan, and Rstudio certainly found a file structure and data vaguely representing what I recall was on the drive. (the file system is NFS+)
When I look carefully at some of the files, however, the data contained looks scrambled: files contain some correct data but do not start at the beginning of what I remember the files to be (starts mid-line), files I which should contain some expected content (e.g. README) appear to contain data that belong to other files, etc.
Seems to me like I've either got the offset wrong or some other RAID parameter incorrect. Does this seems like the correct diagnosis?
Given that this is connected through hardware which I can only connect to a mac (and thus using a tool like ReclaiMe is not possible), how do I go about the job of identifying the proper RAID parameters?
I'm currently trying to work through the "Finding RAID parameters" walkthrough (started searching for the Master boot record hex on disk images) though that search is taking a very long time (24 hours still hasn't found anything, and only 1/2 though one drive image).
If I have to play the game of trying a couple of parameters, given that scanning take a long time to perform (on the entire drive), is it reasonable quickly iterate through possible likely configurations until I come to one which seems 'right'?
Thanks and appreciate any advice.
-BV
Couple weeks back I had what appeared to be a 2 disk failure on my RAID5 6 disk (2Tb each) set-up disk array on my PROMISE Pegasus R6 drive (connected to my Macmini via thunderbolt).
There does not appear to be mechanical failure of the drives, so I proceeded to attempt data recovery via imaging the drives and rebuilding the virtual array using R-Studio.
Each of the drives appear to have imaged OK (took 6 days overall).
Based on a previous system dump using the PROMIS disk util of the array when I was trying to debug it, I think (though I am not sure) of the following RAID parameters:
Disk Order: I'm prettys sure I have the order of the array correct (confirmed via serial number)
Stripe Size: 128 kb
Block Order: "Right asymmetric" is what was given in the subsystem info check (assume that is analogous to Right Asynchronous)
Offset: Unsure
I set of a virtual array with 6 rows, 128kb block size, right asynchronous, and 6 rows. Each image has an offset set to "0 sectors"
I then begun a scan, and Rstudio certainly found a file structure and data vaguely representing what I recall was on the drive. (the file system is NFS+)
When I look carefully at some of the files, however, the data contained looks scrambled: files contain some correct data but do not start at the beginning of what I remember the files to be (starts mid-line), files I which should contain some expected content (e.g. README) appear to contain data that belong to other files, etc.
Seems to me like I've either got the offset wrong or some other RAID parameter incorrect. Does this seems like the correct diagnosis?
Given that this is connected through hardware which I can only connect to a mac (and thus using a tool like ReclaiMe is not possible), how do I go about the job of identifying the proper RAID parameters?
I'm currently trying to work through the "Finding RAID parameters" walkthrough (started searching for the Master boot record hex on disk images) though that search is taking a very long time (24 hours still hasn't found anything, and only 1/2 though one drive image).
If I have to play the game of trying a couple of parameters, given that scanning take a long time to perform (on the entire drive), is it reasonable quickly iterate through possible likely configurations until I come to one which seems 'right'?
Thanks and appreciate any advice.
-BV