Replacement Drive

[Enquiries]

I have a QNAP TVS 672N with 6x Seagate Ironwolf Pro 18Tb drives running in RAID 5. One of the disks has a warning coming up in QTS indicating bad sectors. I have been to SCAN and they are saying delivery of a new drive may not be until Feb '25. B&H Photo is saying these disks are discontinued. Is putting an EXOS 18Tb drive in as a replacement an option? Alternatively, I could put in a 20Tb (or higher) drive and gradually increase the capacity of my NAS as disks get to end of life (not sure I want to do this as I would expect to replace the NAS in 3 - 5 years) which might be sensible if 18Tb is no longer a capacity that Seagate supports going forward and I may need to buy other replacement drives in the short to medium term.

Input most welcome and thanks in advance.