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.

[ed]

It’s concerning when a drive in RAID 5 starts showing bad sectors, so it’s great that you’re acting promptly. Let’s address your options:

Using an Exos 18TB Drive
Yes, an Exos 18TB is a viable replacement option for your Seagate IronWolf Pro 18TB drive. Both drives are CMR-based and designed for 24/7 operation, making them compatible in RAID environments. The Exos series is enterprise-grade, offering:

Higher durability and workload ratings (550TB/year vs. 300TB/year for IronWolf Pro).
A 5-year warranty like the Pro series.
However, Exos drives can be slightly noisier and consume more power, which might not be ideal in a home environment.

Using a Larger Capacity Drive (20TB or More)
Installing a 20TB or larger drive is also an option. In RAID 5, the extra capacity will initially be unused, as the array matches the smallest drive size. Over time, if you replace additional 18TB drives with larger capacities, you can expand the storage pool.

This approach is future-proof, especially if 18TB drives are harder to find.
You can still maintain compatibility and avoid downtime by ensuring all drives are CMR (avoid SMR drives).
My Recommendation
If you plan to replace your NAS in 3–5 years and wish to minimize costs now:

Option 1: Replace the faulty drive with an Exos 18TB if IronWolf Pro is unavailable.
Option 2: Consider a 20TB IronWolf Pro or Exos drive if you’re open to eventual capacity upgrades.
Whichever route you choose, check firmware updates for your QNAP and drives to ensure compatibility and stability. If availability remains an issue, reach out to Seagate’s support team—they might help locate a reseller or suggest an alternative.