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A simplified understanding between NAS & SAN!

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  1. 1. NFS (NAS) vs SAN Differences 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 of data. "Block-reads over NFS and Block-reads over iSCSI are almost identical" NFS:  Requests a certain number of bytes, starting at a given byte offset.  Uses a file handle to identify the blocks. SAN :  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!”
  2. 2. 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 storage appliance. 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 (16TB). 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 Revolutionize storage! 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!! March, 2019