Block level VS File level storage

| Tuesday, December 8th, 2009 | 2 Comments »

I wanted to provide a quick summary of the differences between block and file level storage and how it pertains to VMware. This is not going to be a NAS vs SAN article, but more of the fundamental differences between how they each store data.

Block level data storage

  1. Protocols that use block level: Fibre channel, iSCSI, FCoE etc…
  2. Does not have a file system such as ext3 as overhead.
  3. SCSI commands are sent between the initiator and target.
  4. Data block sizes are fixed.
  5. Storage file system can be VMFS.
  6. Generally a more expensive storage type versus NAS devices that typically use file level data storage.
  7. Generally faster than file level storage. (although things are getting closer)

File level data storage

  1. Generally devices that use file level are NAS, and typically cheaper than SAN’s that use block level data storage.
  2. Uses the file system ext3.
  3. Data is written and read as variable length files. These files are broken down into blocks and then stored onto disk. (this is your overhead)
  4. Cannot support VMFS format.
  5. Cannot support external bootup for ESX/ESXi host servers.
  6. File transfer protocols: NFS(v3), CIFS, HTTP/DAV, FTP, rsync, etc…
  7. Generally slower than block level storage. (although things are getting faster & better everday)

So there you have it. A quick run down on block level VS. file level. I’ll continue to update this article as I run into more useful data points.

  • 線上英語

    Many thanks for this good info. I just logged it and will shortly tell the rest of my friends know. They should think it as interesting as I did.

  • Satish_halemani

    Excellent…sweet n simple

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