RN314 - Possible to access data from drive from another PC without first reformatting it?

I have not tried it with a PC drive (I have done some with a Linux drive), and would not recommend doing it with your volume still in place, but it should be possible to access the drive when mounted internal to the NAS if you have Linux skills.  Read through all of this (maybe twice) before you start.  I'm intentionally vague about the commands you use.  If you don't know them, you are probably going to run into trouble trying this.  It's a complex process, so trying to get a USB case or dock for the drive is probably your best bet.

First, keep your NAS data safe by removing the drives with power off and marking their bay positions so you can put them back in. in the same order

Then install a scratch drive (NOT the one you want to recover data from, this one is going to be re-formatted) and let the NAS build an array.  If you want to use this drive as the one to store your data from the PC drive, make sure the volume is not named data unless your NAS volume isn't named that.  That may require destroying and re-creating the array, which you can do before the NAS is finished creating it..

Next, turn off XRAID.  If you forget this, your drive will be formatted when you install it.  Then, enable SSH and make sure you have access.

Now, install the drive you want to recover data from, use lsblk to see the partitioning, then manually mount the partition that contains the data.  It should not be necessary to reboot, but do so if the drive isn't visible to lsblk.

Now, you can use SSH commands to copy off the data, but you need somewhere to copy it to, like maybe a USB drive you use for NAS backup.,  If you need to copy it to another computer or NAS, that will involve mounting external shares to the NAS, or adding the volume to the available SMB shares, which involves a lot where a USB drive is mounted automatically by the NAS firmware.   If the spare drive you used is big enough, that's also an option.  But the step above about making sure the volume name is not the same as you main NAS array (data unless you changed it when you set up the NAS) is important.  You'll see why later.

If you copied the data to somewhere other than the drive in the NAS, you can just shut the NAS down, put the original drives back in, boot up, and copy the data to the NAS if needed.

If you copied it to the drive in the NAS, you now need to EXPORT the NAS volume from the Volumes page of the GUI.  Then put in the original drive plus the one you just exported.  On boot, the volume from the export should mount on the NAS and you can do what you please with the data.  The import step requires the imported volume name differs from any other in the NAS, thus the need for naming it above.

Once the data is moved over, EXPORT the spare drive volume so your NAS will "forget" it.

If you don't have a spare drive big enough or another place for the data other than your NAS, then you can use this process with a small drive to learn how to make the PC drive accessable before you do it again with your original array still in place.  Of course, here you do not export the NAS array after the copy, you just shut down, remove the PC drive, and re-boot.   And it would be best if you have a backup of your NAS data before you start,

Note that this method does not work especially well to "bucket brigade" the data in small chunks using the spare drive if it's too small.  Once exported, the volume cannot be re-imported as a primary volume.  You have to start over each time you need to move additional data.