Both iSCSI and NAS are both targeting providing storage access over Ethernet using IP. In this case, they both use TCP/IP. The difference is that iSCSI is providing block level access to data while NAS provides file level access. Databases typically use block access for performance reasons (there are many issues here which I won't go into).
The block level access for databases is done with direct attached for Fibre Channel attached SAN storage today to give the performance required in some environments. Both NAS and iSCSI are trying to address the transaction processing market by improving performance. This is being attacked with TCP/IP accelerators (special bus adapters or NIC cards) and in the case of iSCSI, with some of the iSCSI required processing offloaded. As usual, these require new device drivers. You are essentially correct in that iSCSI and NAS are both targeting the same market. The argument that they are less cost than other solutions is probably not true at this point.
The bottom line is that you must understand your requirements for performance, administration, security, support, etc. and make a decision based on that and not on anybody's simplistic rule-of-thumb. One size does not fit all and your requirements may dictate a specific solution.
Evaluator Group, Inc.
Editor's note: Do you agree with this expert's response? If you have more to share, post it in our Storage Networking discussion forum.
Dig Deeper on Ethernet storage
Related Q&A from Randy Kerns
Compare SAN and NAS, and find out what to consider when using each storage system format. Object storage and the cloud are also affecting the storage... Continue Reading
Logical unit numbers are a logical abstraction between a physical disk device and applications. Learn more about LUN use cases and LUN security ... Continue Reading
What is the one hidden gotcha that you'd advise users about if they were shopping for an all-flash storage array? Continue Reading