RAID 1 - drive failed - very slow queries even after drive replaced

Hi,

I am looking for some advice on where to troubleshoot after 1 drive in
a RAID 1 failed.

Thank you.

I am running v 7.41, I am currently importing the data to another
physical server running 8.4 and will test with that once I can. In the
meantime here is relevant info:

Backups used to take 25 minutes, and now take 110 minutes, before
replacing the drive it became clear the backup was not going to finish
since in 120 minutes it had only finished 200mb of 2.8gb.

Before replacing the drive:
-----------------------------------
We noticed all of the queries were slow, many taking over 100 seconds.
After we replaced the drives we noticed the queries are running 40
seconds or more and most are 8 seconds or more where the same query
used to take only 1 second. We have replaced a drive in this RAID 1
before and nothing like this happened. The schema was not touched for
at least 1 week prior to this.

Since replacing the drive I have:
-------------------------------------------
Restored from a backup a few hours before the queries became very
slow.
Reindex all tables
Vacuum all tables
Analyze all tables

Here is what I get with iostat:

iostat -k /dev/sda2
Linux 2.6.26-2-686-bigmem (db1)
avg-cpu: %user %nice %system %iowait %steal %idle
19.61 0.00 8.34 1.60 0.00 70.45