What exactly is RAID and it's advantages?

Ned, you say "the Western Digital RE/RE2 series and the gold standard of performance, the Western Digital Raptors."

Does this mean the Western Digital Raptors are a diffeerent model to the RE/RE2 series?

Or is Raptor a standard term for ALL WD Enterprise drives?

I'm of the opinion that MTBDL (mean time between data loss) is far more important than MTBF (mean time between failure).

You're right, although under a RAID implementation they're both important. Also, under a RAID 1 implementation MTBDL it is the hardware failure that is more important. Obviously this depends on how the RAID controller manages data discrepencies.

Does this mean the Western Digital Raptors are a diffeerent model to the RE/RE2 series?

Yes, the Raptor is a different model altogether where the emphasis is speed over all else. The result is a 10,000rpm (over the standard 7,200rpm) drive with a maximum capaicity of 150GB.

Please be aware that I/O is not actually improved in
multiples as it suggests as there are overheads that
are incurred by the RAID controller in managing the
RAID implementation. Additionally, under Mac OS X the
controller is software based rather than hardware
based so there are performance losses there as well.
It is possible however that the Mac Pro does have a
hardware RAID controller which is implemented as part
of the Intel 5000X chipset and Disk Utilty only
controls it. Someone who knows more about the Intel
5000X chipset might want to confirm or deny this.

This is a nice thread so I thought I would add to it
a little bit here:

Disk I/O is controled by Intel's 6321ESB and it supports
up to 6 SATA devices and 2 PATA devices, which is where
you get the expansion capabilities that are built into
the system. You've got four SATA hard drive bays and
support for up to two SuperDrives. Apple does indeed
still relie on OSX to provide RAID support, so only
RAID 0 and RAID 1 are supported and it IS through
software. It's a very fast implimentation however
and with all 4 CPU cores at even 90% there shouldn't
be much if any speed differences between you MacPro
and most common embeded controlers (hardware) found
in circulation today.

The 5000X as said, does not contain a RAID controller.
It's a very nice chipset however and I feel very good
about having it in this $2500 system - an impossability
on any other platform that I know of. The 5000X deals
with the four FB-DIMM memory channels and has two
independent 64-bit FSB interfaces, one for each Xeon
socket. With two FSBs running at 1333MHz a piece,
there's a total of 21.3GB/s of memory bandwidth
offered if you populate with four identical FB-DIMMs.
Only using pairs will provide you with exactly half
of that bandwidth and maybe actually less than that
depending of some of Apple's design choices. I would
need to test further to be sure which.

The 5000X "System Controller" supports 24 PCIe lanes:
One x16 and one x8. The x8 connects to the ICH which
is the system's "I/O Controller" mentioned above while
the x16 is what drives the double height PCIe slot.

The ICH have another 12 PCIe lanes split off into
two x4's and one x1 for its remaining PCIe slots.
Apple uses physical x16 slots, so each slot can be
any sort of card - video or whatever - this is much
better than typical PeeCee MBs having x1 and x4 slots.
It's because of Apple being smart in this area that
all four x16 slots can seat video cards at once for
a sweet 8-Monitor LCD arayed display. You will notice
this in the system configuration options when you go
to purchase your MacPro system.

I clone every day or two and backup weekly. Even
without RAID, if I didn't do this a hardware failure
would result in data loss so RAID isn't particularly
worse than an independent drive setup.

Ned - Your insight and experience has been invaluable in setting up my system. Can you give me a little more detail on your statement above re: cloning and backup? What software and hardware do you use for cloning and backup? What is your strategy/setup? What is the difference between "clone" and "backup" as you are using them?

Thanks.

They use higher quality parts, which is why WD has not seen the need or that it would make sense, to move the Raptor to 3Gbps mode - and the Raptor has had very few problems, low failure rate, built more to SCSI class standards (and WD didn't need to worry they would be competing against their own non-existent SCSI market).

I really wish you would look on www.wdc.com and check out the drives.

What is your strategy/setup?

It's really simple. My RAID/main/boot drive is cloned to an external FireWire drive using SuperDuper!…

http://www.shirt-pocket.com/

… on a nightly (well… mostly) basis. Using SuperDuper!'s "Smart update" this takes less than 10 minutes so it's extremely painless. This is in actual fact my main source of recovery. Additional to that is a more or less weekly archival backup to DVD using Retrospect…

http://www.emcinsignia.com/

… which is more for a "when all else fails" scenarios as well as for older versions of data. All that is backed up onto DVD is the /Users directory as the OS and applications would be clean installed in the case of a extreme failure so there's no reason for me to waste DVDs on that stuff.

Where I differentiate between clone and backup is that to me a clone is a single instance of your system at one particular moment in time (the time you did it). It holds nothing other than the exact state of yout system at that time so its value can be limited. The nice thing about cloning is that it's quick and simple and costs nothing beyond the original cost of the drive (internal or external).

With a backup I mean a incremental, archival backup where you have copies of all data at each instance you added to the archive. This allows for a more comprehensive recovery beyond the last moment you did a backup. It is more cumbersome as is more costly by does provide more security for your data. The painful part of this is that when you have large files, such at a 55GB Parallels drive image or video files etc, a single bit of change to those files would result in their complete rewriting to DVD. Ouch! So your scheme needs to be very carefully thought out as to the "what's backed up" and how you set up your filter rules.

A combination of both is by far the best and gives you the best of both world with the speed and efficiency of cloning coupled with the historical archival ability of a DVD backup. Having said that, having one or the other is streets ahead of having nothing at all.

Currently my Windows (both Boot Camp and Parallels)/Junk drive is not backed up at all and is something I need to get sorted out.