Data recovery and disk repair questions and discussions related to old-fashioned SATA, SAS, SCSI, IDE, MFM hard drives - any type of storage device that has moving parts
August 30th, 2015, 11:57
I have a 24 x RAID6 that was using a HP P800 Controller. The RAID was used as a NAS using FreeNAS. The data on the RAID is made up of iSCSI containers with WAV files as the content. As such there is no real file structure to determine drive order. Drive #1 and Drive #23 have MBR's (not bootable) which makes me think either the client mixed up the drives, or the drive order is a little unusual. I can see stripe size is 16KB from looking at some of the WAV files. As this is a HP RAID 6 I am assuming RAID type is XOR/Reed Solomon. Drive 24 is also concerning as it seems like an MBR and EFI partition which looks corrupt? I have attached a picture. I am not too familiar with Reed Solomon so not sure if that is parts of the coding.
I can play some files over 50KB so the RAID seems to be assembled correctly but they always fail after a while so I am presuming drive order is not correct. Any ideas how I can determine the drive order?
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August 31st, 2015, 5:39
seek professional assistance "dr-kiev"
August 31st, 2015, 7:48
Try to assemble configuration with delay = 8 or 16 or 32. It's common for HP RAIDs.
August 31st, 2015, 12:21
Alkzndr wrote:Try to assemble configuration with delay = 8 or 16 or 32. It's common for HP RAIDs.
Will do. I have tried 16 following another post in the forum for a similar issue but the RAID did not build. Will try the other delays you suggest and report back. Thanks
chinopk wrote:seek professional assistance "dr-kiev"
I do have a couple of 'go to' guys when things get tough, thanks for the referral.
September 1st, 2015, 7:20
Have you done it?
If you upload some data from each drive, I'll try to determine the order. I need data from the same intervals on each drive, which contains data. Zeroes won't help.
September 1st, 2015, 11:56
Alkzndr wrote:Have you done it?
If you upload some data from each drive, I'll try to determine the order. I need data from the same intervals on each drive, which contains data. Zeroes won't help.
Many thanks. The partition is ZFS with 5 iSCSI volumes Ext4 formatted. If it was NTFS I would agree that we could look at snippets of data and reconstruct, but this is literally just 100,000's of WAV files. Not so easy.....
September 1st, 2015, 12:42
Calculation of ReedSolomon depends on drive order. If it was "standard" RAID6, it would be possible to check drive order by checking ReedSolomon blocks. It doesn't matter what kind of data you have. If it is ZFS RAID-Z2, not "standard" RAID6, the technique will not work. If it is "simple" zfs on "standard" RAID6, the technique will work.
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