RN214 Potential errors and solutions

Thanks for posting the disk info.  This is why your helper said the disks needed replacing:

Device:             sdb
  ATA Error Count:                36
  Reallocated Sectors:            193
  Reallocation Events:            193

Device:             sdc
Health Data:
  ATA Error Count:                57
  Reallocated Sectors:            176
  Reallocation Events:            176

FWIW, I agree with that.  I replace disks before the reallocated+pending sector counts reaches 50.  Though different folks have different ideas on how many reallocated sectors are ok.

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Alexjccim wrote:

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• What error count level should I be looking for?

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I was thinking looking for any increase in the ATA counts.  Though as noted above, I'd replace the 6 TB Ironwolfs, because of the reallocated sectors.  Then keep an eye on the 4 TB drive that also has some ATAs.  Those might be side effects of disk errors on the main drives.

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Alexjccim wrote:

How hard is it for me to buy a new one and hot swap them?

It's not difficult to do the swap.  You just remove one of the disks with the NAS running, mount the new one into the tray, and reinsert it.  Then check to see that the resync has begun.  You'd want for the resync to fully complete before swapping the second one.

One caution - your data isn't protected by RAID redundancy during the process.  And since you have two disks with bad sectors, the resync might fail (due to errors on the second disk).  So it is particularly important for you to have a backup of your data before you do the swap. 

Generally speaking, RAID redundancy isn't enough to keep your data safe even when the disks are healthy.  So you should begin by putting a backup plan in place.  Using USB drives for backup is one approach (usually the least expensive).