My main boot disk is a 240GB EVO 840, I have a 2TB Seagate drive partitioned as D (1TB) & E (1TB) and a 240GB F drive.

The PC rebooted by itself today, when it restarted the Seagate (D & E) had gone. Couple of reboots later and it's back.

I tried to use Macrium Reflect to back it up and it returned:
Backup aborted! - Unable to read from disk - Error Code 23 - Data error (cyclic redundancy check).

So now I'm manually copying anything of importance from D & E to a 1TB & 2TB USB3 drive.

Once this is done I can do a chkdsk or scandisk... and then hopefully backup using reflect.

I've ordered a new 2TB disk which I'll collect on Saturday.

Once I have it what's the best way to swap out the Seagate for the new Toshiba drive ?
Ideally I'd like to keep it as 2 x 1TB D & E drives.