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Vol. 4 No. 2 April 2005

Tap into Windows' hidden resources to make it enterprise-worthy

@exb So, what exactly is a LUN? One of the most fundamental concepts of enterprise storage is the LUN, but it's often misunderstood. Put simply, a LUN is a chunk of storage on a SCSI-based network, including Fibre Channel and iSCSI SANs. The concept comes from SCSI, where target devices (originally an entire disk drive) are subdivided into a few logical units (originally partitions). Each unit is presented to a computer system ("initiator," in SCSI parlance) with a unique number--LUN actually stands for logical unit number. For example, let's say you had a 100GB SCSI drive alone on a SCSI bus configured as target device 0 (all SCSI addresses start at zero). If you partitioned that drive into five 20GB slices, you could address them as LUNs 0 through 4. The fourth slice would be target 0 LUN 3. Because RAID systems don't use disk partitions in the traditional sense, the LUN concept became cloudier. Some early RAID systems did away with LUNs altogether and simply addressed entire RAID sets as targets. Others allowed RAID sets to ...

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Features in this issue

  • Pros and cons of VTLs

    by  W. Curtis Preston

    VTLs aren't perfect, and this tip outlines some caveats about the technology that you need to know before implementing a VTL.

  • First Look: Crossroads Systems' DataMover 240f

    Crossroads Systems' DataMover 240f is a SAN edge device that takes on one of the most vexing backup bottlenecks by keeping data flowing through the network pipes.

  • Are SATA drives ready for the enterprise?

    SATA drives are great low-cost alternatives to pricey Fibre Channel and SCSI drives, but they lack the reliability and performance that mission-critical applications demand. But new technologies are bringing SATA up to enterprise-class standards.

  • Keep track of backups

    Backup reporting tools help track backup failures and determine their cause. Some tools can identify weak links in your backup processes where there's a potential for failure.

Columns in this issue