Re: Identifying harddrives
I'm not sure how to map that dmesg back to a physical device but, you may want to install:
That will allow you to get at the data that your disk keeps about it's general health with:
sudo apt-get install smartmontools
Replace /dev/sda with your device names. You'll want to check the man page for smartctl and probably google a bit to understand the data but, that should help in determining if your disks are dieing.
sudo smartctl --all /dev/sda
Don't try to make something "fast" until you are able to quantify "slow".