Replace data disk

I have a nightly cronjob configured to execute a script which

• runs a SnapRAID sync and scrub when some requirements are met (e.g. number of deleted files do not exceed a threshold)
• and sends me an email to notify me about what happend during the script execution

This is how I got notified that the latest SnapRAID sync could not be executed: Some files on one of the data disks could not be read because of an "Unexpected input/output read error".
This did not really surprise me because SMART was reporting the affected disk to have a 100% estimated probability to fail soon for a while now. Additonally, this already happend before on this disk, but I could always easily fix it by replacing the broken file. Not this time. The issue was affecting much more existing files now (including files I newly added trying to fix the broken ones).

So there was no way around it: I had to replace the disk.