NFS (NAS) vs SAN
From client's (Application) perspective : There are no differences - I am quoting 'Dave Hitz' words
below, he keeps technical matters so simple that it gives some people - heebie-jeebies!
Dave Hiltz’s words of wisdom: At the protocol level, block-reads over NFS and block-reads over iSCSI
are almost identical. It’s true that NFS has lots of fancy requests (which is now substantially strip
down in NFSv4) that iSCSI and Fibre Channel SAN do not, such as to create directories, set
permissions, move files, and so on, but none of that matters when all you do is read and write blocks
"Block-reads over NFS and Block-reads over iSCSI are almost identical"
Requests a certain number of bytes, starting at a given byte offset.
Uses a file handle to identify the blocks.
Requests a certain number of blocks, starting at a given block offset.
Uses a LUN to identify the container holding the blocks.
“With NFS you must divide by 512 to convert bytes to blocks. So what!”
Different container but same matter!
A LUN and a file are both just containers that hold blocks of data, so get over it. It was this similarity
that originally convinced me (Dave Hitz) that NetApp could “unify” SAN, NAS and iSCSI into a single
Key-to: “Unify” was ‘WAFL’ (Filesystem + Volume Manager): When you create an aggregate [Disk
/SSD] the basic building block for Storage, the filesystem is already laid. Hence, when you create a
LUN, you create a LUN out of a ‘file’ (you get it?); Yes a file (special) that is presented as emulated
disk or Logical Unit. Therefore, imposes the maximum LUN limit on NetApp storage no matter what
Ontap version it is. End of the day, it’s the file size limitation that governs the LUN maximum size
It's fair to say that (My tribute): Pele was sent down to play football, Sachin Tendulkar to play Cricket,
Michael Jackson to create pop, Steve Jobs to create PC, Bill Gates to create software and Dave Hitz to
His book: How to castrate a bull! Is nothing like a technical jargon, it's one of the most interesting
and sometime adventurous ride, most recommended!!