Rather than get into why data backups are good and why hardware backup is
good, we first need to find out if Rich even does any backups now. If he
doesn't backup now, he doesn't care about his data or time. His data is of
no value to him, or it can be rebuilt, or recovered somewhere from
elsewhere. His time is of no value to him to reinstall the operating
system, reinstall his applications, and to configure and customize it all
again. Talking about RAID 1 to someone who doesn't do backups now is a
fruitless argument. They aren't backing up now. They won't be backing up
later.

Your point is that adding more drives in a striped RAID 0 set will reduce
reliability. Yes, it will. If the MTBF (mean time between failures) for a
hard drive was 3 years and you add another in the same RAID 0 set then you
get 1.5 years for MTBF. But a non-RAIDed drive with 3 years MTBF could
still tomorrow. If Rich isn't backing up now, he doesn't care about data or
hardware recovery. So RAID 1 won't be an option for him.

I also suspect if Rich is asking about RAID 0 and never mentioned RAID 5
then his RAID controller only supports RAID 0 and 1 (and maybe 0+1). It's
likely he is looking at using an onboard RAID controller on his motherboard.
If Rich had the availability of RAID 5, and if he could afford 2 more drives
instead of just one (since he isn't going to spend any money on backup
drives and media), then he should go with RAID 5 with 3 drives.

It comes down to waiting for a response from Rich to find out if he does
backups now and, if so, what backup device he has or will get. If he
doesn't backup now, does he want to spend the money on yet another drive to
only have it used as a backup with mirroring in RAID 1? Not likely. He
doesn't do backups! If he is willing to spend the extra money to
incorporate backup (data or hardware), will he spend it on the second drive
and use mirroring in RAID 1 (and still not have the speed advantage of
striping), or would he rather spend it on a tape or DVD-+RW drive so he has
the advantage of removable media that can be used in another drive (so he
doesn't have to worry about the drive going bad and becoming unusable for
restoring his system) and even restor to another host? RAID 1 is used to
keep the host running or get it back up quick, not for backing up your
files. RAID 1 is for hardware recovery, not data recovery. Or does Rich
still not bother with backing up his computer and use that same money that
would otherwise be for a backup device (mirrored drive, tape drive, CD-RW
drive, DVD-+RW drive, or external hard drive) and use it for a 3rd drive so
he has 3 drives and can use RAID 5 which offers the speed advantage of
striping along with hardware recovery? Instead of spending money on backup
hardware whether for data or hardware recovery which he does not do
presently, he instead spends it on the 3rd drive which gives him the speedup
plus covers his butt with some hardware recovery. He still has no data
backups (but he didn't have them before, either), he gets his need for speed
satisfied, and he gets some hardware protection despite his lack of
enthusiasm for backing up his data.

I can promote data backups until I'm blue in the face, but if the user
doesn't do it now then it is very unlikely they will employ it later. In
that case, RAID 1 is not an option to that user. RAID 0 is a more
appropriate choice *if* they really have a need for the increased
*potential* bandwidth it can offer. Yes, RAID 0 has reduced reliability but
then the user doesn't care because they're not doing backups now. You don't
rely on a higher MTBF to protect your data - if it's worth protecting. A
RAID 1 setup that has an MTBF of 1.5 years could run a decade before a
hardware fault killed that RAID set. A non-RAID single-channel drive (his
current setup) with an MTBF of 10 years could die tomorrow. A RAID 1 set
with 2 drives each having an MTBF of 10 years could die tomorrow because
static or a surge fried both drives, or the single controller got fried and
has to be replaced (unless you really get pricey to employ duplexing), or
the CPU fried, or whatever occurs within the same host in which the mirrored
drive coexists with the primary drive. The point is that backups which are
on separate media that is removable from the host and usable on replacement
drives or even in substitute hosts is how you backup your data. RAID 1 is
how you provide disaster recovery of your hardware. Unless Rich is using
his computer as a server (and used in a network where other users need it)
then there's little point in providing disaster recovery except based on
your own personal needs and budget.

Alas, when talking to newsgroup posters that inquire how to recover a file
that has been thoroughly deleted and telling them to use their backups, the
response is akin to deer caught in headlights: you get a vacant stare
implying "Backups?", a roll of the eyes, and then "Um, any other
suggestions?". No RAID setup supplants the need for a backup scheme. Don't
confuse hardware disaster recovery with data recovery. RAID 0 gives you a
*potential* speed increase with the reduction in *probable* failure time.
RAID 1 gives you disaster recovery provided only the drive went bad and not
the controller, motherboard, CPU, memory, or other common hardware, but you
get no speedup. RAID 5 gives you the speedup along with the hardware
disaster recovery. None provide you with backups. It is unfortunate that
"backup" can be used to discuss saving a historical image of your files on
removable media or to discuss how to maintain your hardware presence.
Backing up your data is not the same as backing up your hardware.