Need some help on recovering RAID 5 failures

[the FooL]

So I have a Smartstor NS4600.
Single 4TB volume spanned across 4 1TB drives.

I turned on my computer one morning and the NAS is reporting that only two disks for the volume were found.
I tried switching drives to see if it was a problem with the slots, but no go.

So my question is:

Anyone have experience with any software solution for recovering a corrupted partition table (I'm assuming that might be the issue).

What and where is the information stored on the drive so that a controller knows which drives belong to a RAID volume.
I don't believe it's stored it the NAS, because I'm moved all four drives to another NAS box (same model) and it recognized the existing volume, allowing me to recover it for that box.

Thanks.

 

[dave_the_nerd]

The partition table is stored at the beginning of a drive. RAID group membership is probably stored there too. The only other place that stuff is stored is the tail end of the drive.

But if you moved the drives to a different enclosure and everything was recoverable, then it wasn't your drives or RAID.

I just want to point out that if you have 4 1TB drives and a 4TB volume, you don't have a RAID-5. Is it maybe a 3TB volume? Because otherwise, you're hosed in the event of an actual drive failure.

 

[the FooL]

The partition table is stored at the beginning of a drive. RAID group membership is probably stored there too. The only other place that stuff is stored is the tail end of the drive.

But if you moved the drives to a different enclosure and everything was recoverable, then it wasn't your drives or RAID.

I just want to point out that if you have 4 1TB drives and a 4TB volume, you don't have a RAID-5. Is it maybe a 3TB volume? Because otherwise, you're hosed in the event of an actual drive failure.

You're right, it's a 3TB volume.
I meant in the past I was able to move from one Smartstor to another Smartstor and the RAID was recovered.
Which is why I think it's just some corrupted data on the drive.

Now I don't think it will work, because the NAS doesn't think two of the original drives belong to the configuration.

 

[dave_the_nerd]

So you already tried moving to a different box? Bummer.

Does the RAID controller or software have any advanced recovery or rebuild options?

Sorry, but if two of your four drives are hosed, chances are pretty good the RAID array is done. I mean, if the partition map or RAID info is broken, it's probably not the only corrupt data on those disks, you know?

Do you have another set of disks up and running, or are you down-timed until you get this RAID back online? If time is money, I would probably overnight myself some new disks (can't trust the old ones), build a new RAID, and restore from backup.

4x 2TB disks in RAID-10 would be about $400 and give you a small boost in volume size, too.

 

[the FooL]

So you already tried moving to a different box? Bummer.

Does the RAID controller or software have any advanced recovery or rebuild options?

Sorry, but if two of your four drives are hosed, chances are pretty good the RAID array is done. I mean, if the partition map or RAID info is broken, it's probably not the only corrupt data on those disks, you know?

Do you have another set of disks up and running, or are you down-timed until you get this RAID back online? If time is money, I would probably overnight myself some new disks (can't trust the old ones), build a new RAID, and restore from backup.

4x 2TB disks in RAID-10 would be about $400 and give you a small boost in volume size, too.

I'm still trying to determine what factored in the failure, since if for some reason the NAS wrote bad data, I would need to replace it.

Most of my recovery attempts is just to minimize having to re-rip my CD collection
Rest of the data was just backups of something I already had on my PC.

Running some software right now to see how it goes, but not really expecting anything great.

 

[nehalemi7]

I once used http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step to restore an Intel RST RAID that had forgotten that my RAID 5 existed.

 

[Mark R]

Most low-end NASs use linux software RAID, and I suspect that this is what the Smartstor uses.

The RAID config data is stored in the RAID partitions, so if the disks can be read and the partition tables are OK, then a linux live CD should detect and activate the RAID automatically.

Worth trying to connect the drives to the SATA ports on a PC, and then booting a linux live stick/CD and seeing what gets detected.