RAID 1
Making a spare copy of your data
will impact performance, but by
how much?Otherwise known as disk mirroring,
RAID 1 maximizes protection between
two disk drives. Unlike a RAID 0 setup,
two drives linked in a mirror confi gura-
tion don’t double the total capacity of a
single new volume. Rather, the capac-
ity of the volume is determined by the
size of the smallest drive in the array.
The benefi t of mirroring two drives
together is obvious; just consider the
name of the array. Whenever data
is written to a single hard drive, it is
instantaneously written to the other
drive in the array as well. If one drive
fails, you’ll have a copy of all your
data. You can then boot off of the sur-vivor by itself or replace your busted
drive in the array with a working drive.
Your RAID controller will rebuild the
array without interrupting normal fi le
operations and return everything to full
working order.
This kind of setup is ideal for those
who are more concerned about pro-
tecting their data than increasing per-
formance. However, don’t misconstrue
the benefi ts of RAID 1 for a data back-
up solution. A mirrored array is more
designed for those, “Oh crap, the hard
drive just died randomly” scenarios. A
mirrored array won’t protect you from
accidental fi le deletions or malicious
software that wipes out your drive (see
the sidebar below).HANDS ON
Due to the extreme differences
between RAID 1 and RAID 0, we
expected to see dramatically differentresults in the relative speeds of the
two formats. After all, you’re trading
storage speed for sustainability. What
we were unsure about was the perfor-
mance difference between a mirrored
setup and a single identical drive in a
stand-alone confi guration.
As it turns out, the mirrored array
actually performed better than a single
Raptor. We attribute this to our RAID
controller’s ability to select which drive
to read data from—it can use one hard
drive for one data task, while simul-
taneously accessing a different data
request with the other. Not surpris-
ingly, the mirrored array’s write speeds
weren’t as impressive but still bested a
single Raptor drive by about 7MB/s.If one drive’s contents are
always replicated on another
drive in a mirrored RAID
confi guration, RAID 1 is the
perfect backup solution, right?
Wrong. Using a mirrored RAID
as your de facto backup solu-
tion works wonders in certain
disastrous occurrences, like if
one of your hard drives spon-
taneously explodes. But RAID 1doesn’t prevent any of the more
malicious (or user-created) data loss
issues. If you have a virus on one
drive—guess what?—it’s been repli-
cated on the second drive. Or if you
accidentally perma-delete a fi le, it’s
gone on both drives. Grab a third-
party backup program for your fi les
and let RAID 1 take care of the act of
God–type situations.RAID 1 AS A BACKUP SOLUTION?
NO WAY!
MAXIMUMPC NOVEMBER 2007
DONE RIGHTRAID
Best scores are bolded.Burst (MB/s) Average Read (MB/s) Average Write (MB/s) Score XP Loading (MB/s) App. Loading (MB/s) Virus Scanning (MB/s) File Writing (MB/s)
RAID 1 465.9 99.46 109.63 8,085.3 14.90 6.24 82.96 221.53
SINGLE DRIVE 452.1 78.0 102.7 6,329.0 10.42 4.93 77.88 160.51HD TACH PCMARKO5