External hdd as RAID Concatenated Disk?

Discussion in 'Mac Basics and Help' started by EvanLugh, Jan 10, 2008.

  1. EvanLugh macrumors 68000

    EvanLugh

    Joined:
    Aug 29, 2007
    Location:
    Developer land
    #1
    I'm following a tutorial to add my External hdd to add ontop of my Mac's hard drive.
    Unfortunatly, i cannot click 'create' as it's blanked out. Any ideas?
    Thanks.
     
  2. blodwyn macrumors 65816

    Joined:
    Jul 28, 2004
    Location:
    Portland, Oregon
    #2
    You're out of luck if you're trying to create a RAID set using the disk you're currently booted from. You can only create a RAID set from other mounted volumes. One way to achieve what you want is to:

    1) Clone your internal Mac boot disk to another disk and boot from it
    2) Create a RAID set using your internal Mac disk and the external
    3 Clone the disk you're booted from onto the RAID set
    4) Reboot from the RAID set
     
  3. EvanLugh thread starter macrumors 68000

    EvanLugh

    Joined:
    Aug 29, 2007
    Location:
    Developer land
    #3
    I was doing it from the external. Therefore doubling the amount of space 'on my mac'.
     
  4. blodwyn macrumors 65816

    Joined:
    Jul 28, 2004
    Location:
    Portland, Oregon
    #4
    Maybe I'm misunderstanding, but you need 3 disks to do what you're attempting. One disk to boot from, and two additional disks to create the RAID with

    Also be aware that if you're concatenating the internal and external to make a single larger volume, that a failure in either drive will be fatal to the volume. So you're roughly doubling the risk of losing your data (assuming similar MTBF for both the disks) and therefore making a backup strategy even more important.
     

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