Thanks to everyone for the good advices. Currently I plan to build a
5x500GB raid-6 from new drives and restore the data from the backup.
I'm keeping the original set of 4 offline just in case I need to
recover anything from it.
I still have a couple of questions I hope someone can help me with.
1. Can I still add the original sde back to the raid-5? While I was
doing rebuilding, I believe some files were modified by the OS and the
old sde would be out of sync.
2. Quite a few people talked about "scrubbing" the raid, can someone
point me to somewhere I can read more about it? I'm new to the list.
I tried googling and reading the list wiki and had a hard time finding
a tutorial for setting this up.
Regards,
DS