I think describing the heads as moving in and out is more appropriate since they're mounted on an armature, like a record player, and not forward or backward. I often use record players as a description for clients when they ask how drives work.
In my writing, I try to avoid use 'but' and things like it (however, etc.). Replace the word 'but' with 'and' as an exercise to see how it changes your readers' perception.
You've got a couple sentences that are like Yoda. Eg, by doing this, and it's unnecessary.
Similary, the logical volume... You missed a comma. The same occurs in drive impressions, the stack.
A good article, and a great way to open discussion on SANs and how volumes, drives and RAID presentations can be partitioned or utilized efficiently.
