The following rules and recommendations CX systems:
You cannot use any of the disks 000 through 004 (enclosure 0, loop 0, disks 0-4) as a hot spare in a CX-Series system.
2) The hardware reserves several gigabytes on each of disks 000 through 004 for the cache vault and internal tables. To conserve disk space, you should avoid binding any other disk into a RAID Group that includes any of these disks. Any disk you include in a RAID Group with a cache disk 000-004 is bound to match the lower unreserved capacity, resulting in lost storage of several gigabytes per disk.
3) Each disk in the RAID Group should have the same capacity. All disks in a Group are bound to match the smallest capacity disk, and you could waste disk space. The first five drives (000-004) should always be the same size.
4) You cannot mix ATA (Advanced Technology Attachment) and Fibre Channel disk drives within a RAID Group.
5) Hot spares for Fibre Channel drives must be Fibre Channel drives; ATA drives require ATA hot spares.
6) If a storage system will use disks of different speeds (for example, 10K and 15K rpm), then EMC recommends that you use disks of the same speed throughout each 15-disk enclosure. For any enclosure, the hardware allows one speed change within an enclosure, so if need be, you may use disks of differing speeds. Place the higher speed drives in the first (leftmost) drive slot(s).
7) You should always use disks of the same speed and capacity in any RAID Group.
8) Do not use ATA drives to store boot images of an operating system. You must boot host operating systems from a Fibre Channel drive.


  1. Anonymous Says:
  2. Nice to know. Thanks!

    - Alex

  3. Patrick Says:
  4. Nice one! :)

  5. Anonymous Says:
  6. I will add here. For hot spare disk(s) you should use biggest disk in a storage system. For example we have 133 GB and 266 GB FC disks in a CX4 system, we use 266 GB disk for hot spare.

    "From russia with love..."

  7. Anonymous Says:
  8. did i really need to add hot spare disk for a new raid based on 5x600Gb disk.
    I currently have 133, 266Gb disks and i really need a Lun of 2Tb but only 5 disk emplacements free.

  9. Anonymous Says:
  10. Nice one here!

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