I lost data to this kind of problem[1]. The linux dm-raid handles these kind of failures extremely poorly (or did at the time), even when one following all available tutorials. (When I reported my experience one developer said I should have set a cronjob to recursively md5sum my / every week or so - not exactly user-friendly, and not mentioned in any of the tutorials). When you attempt to rebuild a dmraid array, even a raid6 one, expect to lose all your data.
Now I use ZFS (on FreeBSD), which handles these kind of errors much more gracefully; if there's an isolated URE you might lose data in that particular file, but it won't destroy the whole array.
[1] Yeah yeah, RAID is not a backup. I'm talking about data I didn't consider worth the cost of backing up, as a poor student at the time.
Yeah, now I've near 120 tb of data under ZoL (ZFS on Linux, currently on master as time of writing), replicated at 5 min interval between two datacenters...
Now I use ZFS (on FreeBSD), which handles these kind of errors much more gracefully; if there's an isolated URE you might lose data in that particular file, but it won't destroy the whole array.
[1] Yeah yeah, RAID is not a backup. I'm talking about data I didn't consider worth the cost of backing up, as a poor student at the time.