scavenge RAID drive of unknown origin

The best plan would be to connect it just like a normal "second" drive in your desktop machine, and then use a utility to Zero Fill that unit. WARNING!! A Zero Fill will DESTROY all old data on the drive you do that to, which IS what you want for this old drive. Just be VERY sure you apply the Zero Fill to that drive only, and NOT to any other drive in your system.

A Zero Fill writes just zeros to EVERY Sector of the drive, including the area that had info about the old RAID uses. As a side benefit, it triggers an internal test routine on every Sector, so that any that are weak or faulty will be replaced from a stock of known-good spares. When it's done, the drive will have NO "Bad Sectors" in use, just like a new drive.

The DBAN utility package (should be able to download free) contains a Zero Fill tool. Some HDD makers have good disk diagnostic utility packages you can download for free from their websites and they contain a Zero Fill utility also. But usually these are only to be used on HDD's made by that company. So, if your old HDD was by WD, get their Data Lifeguard utility. If it's from Seagate, get their SeaTools. Each of those is available in "For DOS" and "For Windows" versions. I prefer the "For DOS" one that you must burn to a CD-R disk to make a bootable utility DC you can boot and run from with NO working CD in your system. But in your case, maybe the "For Windows" version that you run under a Windows OS on a computer that is working just fine would do your job nicely. The advantage of these latter two packages is that they also contain substantial disk troubleshooting diagnostic tools for your HDD that can be useful.

When you have completed the Zero Fill (it takes a while, so be patient!) the HDD is completely empty just like a new HDD. So you have to prepare it for use. IF you are Installing Windows to it, the Install process will take care of Partitioning and Formatting for you. But if you are just adding it as a storage drive in a machine that already has Windows installed and running from a different HDD, then use the Windows Disk Management tool for this. In Disk Management look for it in the lower right area where hardware that Windows cannot understand yet is found. RIGHT-click on it and choose to Create a New Simple Volume. Most of the default settings will be right, but this disk will NOT need to be bootable if you are only using it for data.

Popatim is right. Doing that simple process will re-Partition and Format the drive so you can use it as a single unit.

My recommendation of doing a Zero Fill is for a slightly different reason. Doing that would remove any malware that might have been on it, although that is VERY unlikely. But doing it also forces the self-diagnostic routines that find and replace any weak or bad Sectors, and there MIGHT be some of those on an older drive. That process, internal to HDD units, is different from (and better than) the testing for Bad Sectors that a Windows Full Format does.

I forgot to mention something. IF you choose to do the Zero Fill process, then Inialialize it separately, there is another Formatting option to change in that last process. Since you have just completed a full diagnostic and fix routine, there is NO need to let Windows duplicate a lot of that work by doing a Full formal. Have it do a Quick Format instead, and save time.

The best plan would be to connect it just like a normal "second" drive in your desktop machine, and then use a utility to Zero Fill that unit. WARNING!! A Zero Fill will DESTROY all old data on the drive you do that to, which IS what you want for this old drive. Just be VERY sure you apply the Zero Fill to that drive only, and NOT to any other drive in your system.

A Zero Fill writes just zeros to EVERY Sector of the drive, including the area that had info about the old RAID uses. As a side benefit, it triggers an internal test routine on every Sector, so that any that are weak or faulty will be replaced from a stock of known-good spares. When it's done, the drive will have NO "Bad Sectors" in use, just like a new drive.

The DBAN utility package (should be able to download free) contains a Zero Fill tool. Some HDD makers have good disk diagnostic utility packages you can download for free from their websites and they contain a Zero Fill utility also. But usually these are only to be used on HDD's made by that company. So, if your old HDD was by WD, get their Data Lifeguard utility. If it's from Seagate, get their SeaTools. Each of those is available in "For DOS" and "For Windows" versions. I prefer the "For DOS" one that you must burn to a CD-R disk to make a bootable utility DC you can boot and run from with NO working CD in your system. But in your case, maybe the "For Windows" version that you run under a Windows OS on a computer that is working just fine would do your job nicely. The advantage of these latter two packages is that they also contain substantial disk troubleshooting diagnostic tools for your HDD that can be useful.

When you have completed the Zero Fill (it takes a while, so be patient!) the HDD is completely empty just like a new HDD. So you have to prepare it for use. IF you are Installing Windows to it, the Install process will take care of Partitioning and Formatting for you. But if you are just adding it as a storage drive in a machine that already has Windows installed and running from a different HDD, then use the Windows Disk Management tool for this. In Disk Management look for it in the lower right area where hardware that Windows cannot understand yet is found. RIGHT-click on it and choose to Create a New Simple Volume. Most of the default settings will be right, but this disk will NOT need to be bootable if you are only using it for data.

No need to zero fill or dban a drive that only held fragments of the dataset.

Just connect it to a sata port, open disk management, initialize it, followed by a full format instead of a quick (to tests the drives sectors) if you wished. Otherwise a quick format will have the drive usable to you much quicker. The larger the srive, the longer a full format takes.

Your story of the DBAN experience suggests to me strongly that the HDD has major hardware problems. If DBAN estimated, on the basis of 8 hours' work experience, that it would take 500 hours to complete the job, it was having MAJOR errors very frequently as it tried to write to the HDD. My guess is that you should abandon this plan and get a new HDD.

IF you want to try to proceed, I'd stop with the Zero Fill and start now with actually diagnosing the HDD for hardware problems. That may confirm my suspicions, or it might point to something fixable, but I doubt the latter.

Run diskpart's clean or clean all command on the drive from an elevated command prompt though I fell that PaperDoc is correct; something is wrong with that drive.

https://www.sevenforums.com/tutorials/52129-disk-clean-clean-all-diskpart-command.html