A Fresh Backup (existing data only): If you're installing and
configuring hardware RAID on a fresh system with no OS (your best
option), or are adding disks for a separate array, skip this.
Otherwise, back up your important data. Best practice is to have three
copies of your data: the original, a backup, and a backup of the
backup, preferably offsite.
If you have existing data that you want on the array, you'll need to
back it up, then restore it from a backup you make before creating
your array--a process that writes new data to your hard drives
regardless of what's there. This is not necessary with Windows
software RAID 0, however, it's far faster than letting Windows re-sync
(copy the data to) the mirror in the background.
Transferring an existing operating system is tricky, and with older
versions of Windows, sometimes impossible. See "Transferring Existing
Windows Installations to RAID" on the next page for instructions.
Windows Software RAID: Starting with Windows XP, Microsoft integrated
RAID functionality into its operating systems. What type depends on
the flavor of Windows:
Windows XP allows spanned volumes (one volume over two or more disks), aka JBOD.
Windows Vista Ultimate allows JBOD and RAID 1 striping.
Windows 7 Home allows JBOD and RAID 1 while Professional and Ultimate add RAID 0 mirroring. Windows 2000 Professional also has
JBOD, 0, and 1.
Windows Server operating systems from 2000 on have JBOD, 0, 1, plus support for RAID 5 distributed parity.
Windows RAID offers several advantages. You can create arrays from
within Window Drive manager so there's no BIOS to configure. It's also
more flexible with mirrors, allowing you to create them from existing
volumes containing data, as well as delete either half of a mirror
with the other remaining intact. You can mirror individual partitions,
including partitions from different drives onto a single drive.
The disadvantages are that other operating systems, such as the Linux
used on repair discs, can't see Windows software RAID partitions which
use Microsoft's dynamic disk technology. Also, maintenance performed
by Windows when it feels it's needed, which can occur any time there's
a configuration change, hurts performance while in progress. Restoring
mirrors isn't as dead simple as it is with a hardware solution either.
Though you'll see a lot of talk about hardware RAID being faster, this
discussion predates modern CPUs which can easily handle the overhead.
Windows RAID is actually quite fast.