Background

I'm working with an 8TB spinning disk that is formatted in RAID. I know RAID is usually used for multiple-disk arrays, but for some reason this disk was set up as RAID by itself, as I understand.

This 8TB drive was used to store data, separate from the main drive we use for Ubuntu. I'm a bioinformatician in academia and our computer help desk (experienced in data recovery) is working on helping us with all of this. It all started when they tried installing Windows dual boot on a separate hard drive and this somehow led to an inability to boot into the Ubuntu drive that the 8TB drive was mounted on. We've since been unable to mount the 8TB drive (which is separate from the Ubuntu boot drive).

Current situation

They attempted recovery of the 8TB drive using Raise Data Recovery. This resulted in successful recovery of files in base folders (e.g. /data/some_data.txt) with no corruption... but everything within subfolders is zero bytes (e.g. /data/more_data/some_more_data.txt). The metadata all appears correct for these files, although they appear to be zero bytes.

Questions and next steps

What might be the cause of this?

Is there anything I can suggest our help desk try to fully recover this data within subfolders?

Better yet, maybe we can successfully remount this drive and avoid the need for data recovery...?

Any tips would be greatly appreciated, whether using Raise or other tools. We have a backup, but not very recent, and I'll need to spend a week rewriting code if they can't recover this.

Our help desk is closed until Monday and I just found this problem with the partially-recovered data after they closed for the day.

Thank you!

Nope.
Really, beacuse makes me question their ability as even a help desk. So you don't have a backup then.

It's difficult to jump in half way especially with so many assumptions already made. From the sounds of it someone trashed the logical structure installing ubuntu. The zero length files are likely a result of the drive being SMR and trim the files you have are probably from a raw scrape. If the data is important I'd suggest you leave the drive turned off and contact a pro, if your data is still there this should be an straight forward logical recovery. If the data is not important to you , clone the asap and get some screen shots from DMDE so we can see what's going on.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

We could say try this and try that but it would all be useless, if one really wants to recover this thing, would need to investigate it deeply on sector level in order to set up an idea of what's going on.

Giving any 'tips' without seeing the structures would be very unprofessional imo. Guiding somebody who has no insight with file systems is pretty much harder than doing the job.

it seems you are right in the middle of it :s

To be on the safe side, the first thing is to image it without trying to mount.
If you ever try to mount it, do it read-only.
I would start from the beginning, finding out what FS is on it, checking the superblock, the group descriptors if it's EXT, if they are in order, etc, but really, there are quite some questions open.
pepe

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Adatmentés - Data recovery

Not enough experienced.
Using basic version of DR software and not understanding how one drive can bee used as "RAID". And inability to connect properly drive to a separate PC for further research, which is required and most important action.

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Angel Data Recovery

I see plenty of cases where a user has selected RAID mode in BIOS for a single drive. Maybe that's what the OP means?

This is not a real RAID, of course.

Edit: I seem to recall that AMD's RAIDxpert can reconfigure the logical sector size for the "RAID". I think 1KB, 2KB and 4KB sectors are possible, but my memory is a little hazy. If I'm right, then the single drive may be seen as a virtual drive with a non-standard sector size.

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A backup a day keeps DR away.

See https://forums.tomshardware.com/threads/disk-manager-says-3tb-hdd-with-content-on-it-needs-to-be-initialized.2111768/#15036031

AMD's RAIDxpert selected a sector size of 1KB for a single 3TB drive in a RAID "array".

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A backup a day keeps DR away.

Thank you fzabkar. Is this the same thing as "virtual RAID"? Is there a good rationale for setting up a drive in this way? How do we know if we need to send data recovery services this one drive, or another in addition?

DR-Kiev, everything they have done was with the hard drive connected to another computer in "read only" mode. Sorry, I should have explicitly made that clear...

Lardman, how could installing Windows on a separate hard drive trash the logical structure on a separate Ubuntu boot drive?

Is there any further information I could provide that would be helpful in answering my questions?

We are looking into hiring external data recovery professionals, but hope to avoid the (taxpayer-funded) expense of doing so, especially since it seems like we might be so close to getting the data back.... After all, the metadata is all intact.

@help_an_academic, could you please tell us the model number of the drive? That will tell us whether it is an SMR model which may be subject to TRIM.

Can you show us the drive's Partitions window in DMDE?

https://dmde.com/

Something like this ...

http://www.users.on.net/~fzabkar/DMDE/DMDE_Elements-8TB_Partitions.jpg

My observations in regard to RAID-ing a single drive are in relation to older systems that were subject to a 32-bit LBA limit. AMD's RAIDxpert BIOS circumvented this limit by increasing the sector size seen by the OS. Normally the maximum capacity would be 2TiB for drives with 512-byte LBAs, but these limits could be increased to 4TiB, 8TiB and 16TiB if the sector sizes were increased to 1KiB, 2KiB, and 4KiB, respectively. It seems that I'm drawing a long bow, but I can't think of any other logical reason why anyone would configure a RAID with a single drive.

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A backup a day keeps DR away.

You're assuming that's what actually happened.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/