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Please clarify what do we mean by LUN and Array ? and if they are similar in meaning?.

The confusion is because both are presented to specific servers by the combination of different Hard disks or individual Hard disk ( correct me if am worng )

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A LUN (Logical Unit Number) is a number used to uniquely identify any device that is attached to a SCSI device chain, or anything that emulates a SCSI device chain.

Some devices that could be attached to a device chain and would be assigned a LUN include:

  • A single hard disk.
  • An array of hard disks.
  • A tape drive.
  • A CD-ROM drive.

It's important to remember that while SCSI is mostly deprecated today, many operating systems and devices emulate SCSI-like bahavior. This includes SAN technologies like iSCSI and Fiber Channel, which you may be referring to here.

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Great answer Kyle but if you don't mind I'd like to state in Fisher Price terms that in general a LUN is a bit of disk space on an array that's presented to one or more clients. – Chopper3 Jul 6 '11 at 14:00
SCSI is not deprecated. SCSI is a command set that is still very alive. Yes, the old parallel SCSI interconnect is on death's door, but SAS, FC, iSCSI, etc. are all technologies that use the SCSI command set that aren't going away any time soon. – EEAA Jul 6 '11 at 15:19
@ErikA - +1 Good point. – Kyle Smith Jul 6 '11 at 17:33

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