"Pete E" said:
Hi,
Is there anyone out there who can supply information for setting up a RAID
array from the very beginning?
I have tried googling and found that everything starts from having 2 or more
drives etc etc. Trouble is that nobody tells you about having 2 drives and
whether to set the jumpers for Master, Slave or whatever. Can I partition
the drives first, obviously they would be partitioned the same.
Specs are:
Asus P4P800E-deluxe with 2x WD1200JB drives.
Unfortunately when I tried to browse the driver/software CD that came with
the mobo, I found that it was no good and wouldn't read.
I won't be able to replace that for a while now, anyone got a copy they can
let me have?
TIA
Regards
Pete.
First of all, I'll start by saying I've never set up a RAID, so
this is just some guesses.
A RAID works best, if the bandwidth of the drives is "spread"
over the interfaces. If the RAID uses PATA, for example, then
placing a single drive on each IDE cable is the best you can do.
The single drive would be jumpered as a master, or master/single
drive, depending on the brand of drive.
With SATA, the math is simple, because there is only a single drive
per cable anyway.
There are two kinds of RAID on these simple controllers. Mirroring
(two drives with identical data on them) or striping (files are
interleaved over the two drives in chunks called the stripe size).
Mirroring is for reliability, as a single drive failure lets you
continue working. Striping is for performance, as two disks have
more bandwidth to offer that way. The size of the chunk used
(stripe size) determines whether the array works best with large
files or small files.
To start a mirror, you can enter the RAID BIOS at boot time (via
some particular key press during POST), and when you declare two
disks as a mirror, the BIOS writes the membership info in a
reserved sector on each disk, then the BIOS "builds" the array,
by doing a sector by sector copy of the data from the "good"
disk, to the backup disk. If neither drive has any data you
care about, there might be an option to start up without doing
any copying at all ("Create and duplicate" versus "Create").
The stripe configuration is easier, in that there is no data to
duplicate - each drive will have unique info on it, after it
is formatted.
Once configured (and duplicated if a mirror), you can boot.
If doing an immediate OS install on the disk , there will be an
opportunity to press "F6" and install a driver for the OS. If
the disks are only data disks, you can install a driver on your
boot disk, so the system can see the RAID. Some chipsets are
snotty, in that they require the presence of the RAID first,
before they'll allow you to install the software, which can
lead to "chicken versus egg" problems on some Southbridge
RAID interfaces.
To review again, with the mirror, you could partition and format
one drive first, but you'll need to use the "Create and Duplicate"
option for the other drive to have the same info on it. If
you assemble the RAID mirror first, then you can partition and
format the array, and save the time needed to copy the primary
drive to the backup. For the most part, it pays to configure
any chips first for RAID, build the array (whether mirror or
stripe), then install driver via "F6" during install (if a
boot disk), or boot the system, install a driver for the RAID,
then fill the array as a data-only array.
Like any disk drive, it also pays to fill up the disk with large
files, to test for the possibility that the OS is not properly
prepared to handle a logical disk larger than 128GB. I like
to copy the same 1GB file over and over again, onto the empty
disk, until it is full. If the file system is not corrupted by
doing this, then the install is good to go. I then use a small
checksum program, and checksum all the files, and they should
all return the same checksum if there are no problems. This
passes a lot of data over the interfaces, so if there is
something marginal, you might find it before good data is
put on the disk.
With the mirror configuration, it pays to experiment with how
to operate the array when one disk fails. If you don't understand
how to repair a mirrored array, there is no sense trusting your
data to be safely stored on it.
Both mirrors and stripes need to be backed up, as you never know
what kind of hardware failure might destroy them all (like a bad
PSU). A stripe is a particularly bad choice for a boot disk, as
with two disks, there is twice the opportunity for the array
to be broken.
(Drivers)
http://www.asus.it/support/download/item.aspx?ModelName=P4P800-E Deluxe&Type=All
(User manual - see section 5.6 for RAID info)
http://www.asuscom.de/pub/ASUS/mb/sock478/P4P800-E DX/e1526_p4p800-e_deluxe.pdf
HTH,
Paul
