02-01-2009
I don't see how putting them on the same channel will degrade performance to a significant degree. The theoretical limit on SATA is 300MB/s and I have not seen any drives that reliably push more than 90MB/sec on for more than a few minutes at a time. The drives I am going for are lower power 5400-7200rpm variable rotational drives.
As far as the drives themselves, I was going to use a tool WD provides to enable RAID optimized TLER to prevent deep recovery on failed write/read as this could cause a drop on RAID performance (The main difference in their RE series drives).
As for the file systems, I usually break into more than 3, giving /boot, /, /usr, /srv, /home, var and /tmp their own, as well as probably going with a swap partition on the boot drive and a swap file on the array, at least until I get the boot drives mirrored. Then I will not use the swap file any longer and only use the partition on the boot mirror.
I had always planned on LVM for the devices, to aid in the management, or if not LVM, I thought perhaps about using EVMS, but with the reduced support of it, it made me hesitant to try it.
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LEARN ABOUT REDHAT
raidstart
raidstart(8) System Manager's Manual raidstart(8)
NAME
raidstart, raidstop, - command set to manage md devices.
SYNOPSIS
raidstart [options] <raiddevice>*
raidstop [options] <raiddevice>*
DESCRIPTION
RAID devices are virtual devices created from two or more real block devices. This allows multiple disks to be combined into a single
filesystem, possibly with automated backup and recovery. Linux RAID devices are implemented through the md device driver.
If you're using the /proc filesystem, /proc/mdstat gives you informations about md devices status.
Currently, Linux supports linear md devices, RAID0 (striping), RAID1 (mirrroring), and RAID4 and RAID5. For information on the various lev-
els of RAID, check out:
http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/
for new releases of the RAID driver check out:
ftp://ftp.fi.kernel.org/pub/linux/daemons/raid/alpha
Avaible commands are :
mkraid : configures (creates) md (RAID) devices in the kernel, banding multiple devices into one.
raidstart : activates (starts) an existing 'persistent' md device
raid0run : activates old nonpersistent RAID0/LINEAR md devices
raidstop : turns off an md device, and unconfigures (stops) it
By default, a systems RAID configuration is kept in /etc/raidtab, which can configure multiple RAID devices.
All of these tools work similiarly. If -a (or --all) is specified, the specified operation is performed on all of the RAID devices men-
tioned in the configuration file. Otherwise, one or more RAID devices must be specified on the command line. For example:
raid0run -a
Starts all of the 'old' RAID0 RAID devices specified in /etc/raidtab. If only /dev/md1 should be started, the following command should be
used instead:
raidstart /dev/md1
OPTIONS
-a, --all
Apply the command to all of the configurations specified in the config file.
-c, --configfile filename
Use filename as the configuration file (/etc/raidtab is used by default).
-h, --help
Displays a short usage message, then exits.
-V, --version
Displays a short version message, then exits.
NOTES
The raidtools are derived from the md-tools and raidtools packages, which were originally written by Marc Zyngier, Miguel de Icaza, Gadi
Oxman, Bradley Ward Allen, and Ingo Molnar.
BUGS
no known bugs.
SEE ALSO
raidtab(5), raid0run(8), raidstop(8), mkraid(8)
raidstart(8)