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Software Disk Mirroring and Dynamic Disks

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Software Disk Mirroring and Dynamic Disks
Last Updated: 04 Nov 2003

*** PLEASE NOTE: Link(s), If Provided, May Be Wrapped ***

With the cost of hardware RAID as low as it is, I cannot
in good conscience recommend the use of Software Mirroing
for data redundancy.

Also, be advised that only the NT/2000 Server products
support Software RAID.  NT Workstation and Win2K Pro only
support Volume Sets (and Dynamic Disks for Win2K) as a
means of combining non-contiguous disk space across many
separate physical disks.  This provides NO Fault Tolerance.

If, despite this info, you choose to use Software RAID,
there are several caveats that you should be aware of:



Windows 2000 and XP support Dynamic Disks which do away
with the idea of Primary and Logical partitions.  Using
Dynamic Disks allows you to add software RAID to Windows
Server OSes **BUT** there are no 3rd party utilities
which support Dynamic Disks, and the only OSes that can
read from a Dynamic Disk locally, are 2000, XP and later.

Although you can create a RAID0 array in software under
XP Pro, you cannot boot from it.



Here are some 3rd party products that purport to enable
Software RAID on Windows NT, 2000 and XP:



• I won't use Software RAID even at home.  ATA RAID is
  too inexpensive to ignore.

• I've never tested WinRaid, and don't see any reason
  to, given my earlier statements.

• Software RAID in 2000 consumes far less CPU cycles
  than it did under NT4

• If you enable Dynamic Disks, you will not be able to
  use any 3rd party disk partitioning or cloning utils.