It's A Digital Disease!

The original post: /r/datahoarder by /u/Johnny__Derpp on 2025-04-14 01:55:19.

I have a RAID 5 setup with 8 1.5 TB drives and every time a drive has failed I've replaced it and rebuilt with no data loss, except for this most recent time. I had a drive start to fail and even though it came back up I replaced it and rebuilt it. However, a big chunk of the data is still gone and a partition of about 1.5 TB is unable to be accessed (maybe 2 TB total data). I have some old backups but they're like a year out of date so I'd like to know how best to try and recover this data if anybody has had this issue.

Anybody know the probable mechanism for this avenue of data loss even though I thought I had protection from a single drive failing? At least so I can try to prevent it going forward but more hopefully so I can start the process of googling data recovery software for that style of failure? (3ware 9650se with a couple of seagate 1.5TBs from like 2009 as the oldest drives, newer ones are 2-3TB toshibas and a western digital)