I have been concentrating on storage for some time now and if you are trying to understand storage basis, here is a great list of documents covered by Josh Townsend in his blog.
I was lucky to hit this early than many of you wanted to, I hope this helps you to get a clear understanding on the basic ground of storage. Josh has smartly split down storage in VIII different units starting from basic to advanced concept, which makes it very easy to understand. I have added topic and link to respective portion in Josh blog. I am sure you will find it very useful.
Thanks to Josh for his contribution.
Part I: An Introduction
Part II: IOPS
Part III: RAID
Part IV: Interface
Part VI: Storage Workload Characterization
Part VII: Storage Alignment