Differences between version 7 and predecessor to the previous major change of SoftwareRaid.
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| Newer page: | version 7 | Last edited on Thursday, March 18, 2004 12:09:35 pm | by JohnMcPherson | Revert |
| Older page: | version 3 | Last edited on Saturday, January 10, 2004 12:28:58 pm | by JasonCater | Revert |
@@ -1,11 +1,13 @@
-Linux SoftwareRaid is a feature of the LinuxKernel that allows RAID to be performed in Software rather than in Hardware. See SoftwareRaidvsHardwareRaid
for more details.
+Linux SoftwareRaid is a feature of the LinuxKernel that allows [
RAID]
to be performed in [
Software]
rather than in [
Hardware]
. See SoftwareRaidVsHardwareRaid
for more details.
If you are wanting to setup SoftwareRaid on a Linux Machine you should first read the [HowToSoftwareRAIDHOWTO] which is an excellent introduction to RAID in general. __However__ the [HowToSoftwareRAIDHOWTO] was written several years ago towards the end of Kernel 2.2's lifespan while Kernel 2.3 was in development and before Kernel 2.4 and as such is not up to date with how you setup SoftwareRaid under linux today.
+
+(A more recent version is located here: http://unthought.net/Software-RAID.HOWTO/)
As far as I know most distributions today (and definitely Debian Woody) use a utility called ''mdadm'' to administer SoftwareRaid devices on a Linux system. mdadm can be obtained from
http://www.cse.unsw.edu.au/~neilb/source/mdadm/
-Or in Debian
+Or in [
Debian]
apt-get install mdadm
Or Add your favourite distribution here.
Most of the commands and configuration files mentioned in [HowToSoftwareRAIDHOWTO] are superseded by mdadm which is the do-it-all SoftwareRaid tool for linux.
@@ -13,9 +15,9 @@
!!! How To Setup a machine using Software RAID-1
Allthough I setup this machine up with Debian I am pretty sure that most of the steps listed below will be distribution independent. We will start from the basic hardware that doesn't do anything useful and progress until we have a machine that boots up into a full working Debian install off the raid array.
-The machine that I used for this configuration has a Intel S845WD1-E Motherboard with two on-board IDE channels plus an extra two channels controlled by a Promise PDC20267 RAID chipset (commonly known as a Promise FastTrak100). Unfortunately Promise is not clever enough to release open source drivers for the RAID portion of this chipset so it is only useable as an IDE controller under linux. The rest of the machine is configured as follows. There is one 40GB Seagate IDE Disk on each of the FastTrak's channels. We want to use these two disks to create a RAID-1 array for redundant storage.
+The machine that I used for this configuration has a Intel S845WD1-E Motherboard with two on-board [
IDE]
channels plus an extra two channels controlled by a Promise PDC20267 RAID chipset (commonly known as a Promise FastTrak100). Unfortunately Promise is not clever enough to release open source drivers for the RAID portion of this chipset so it is only useable as an IDE controller under linux. The rest of the machine is configured as follows. There is one 40GB Seagate IDE Disk on each of the FastTrak's channels. We want to use these two disks to create a RAID-1 array for redundant storage.
Assuming that the physical installation has been completed correctly with a single disk on each IDE channel, 80pin IDE cables, etc. The next problem we face is that the Debian installer (an all other distributions installers?) cannot install directly onto a raid array as the standard kernels do not have software raid support included. To get around this problem I used the first method described in [HowToSoftwareRAIDHOWTO] of placing a 3rd disk on the first on-board IDE channel and installing a Basic Debian install on to that.
!Install Debian onto a different disk to the ones in your RAID array (On the first on-board IDE controller)
@@ -193,4 +195,15 @@
Finally, install the new lilo configuration
# chroot /mnt lilo -v
and continue with the rest of the instructions.
+
+! Recent Debian Kernels do this Automatically
+
+The most recent versions (eg [LinuxKernel2.6]) of the Debian kernel-image packages
+build a new initrd image upon installation. They should automatically notice if the
+root device is /dev/md* and arrange for the appropriate modules to be present in the
+initrd image and loaded appropriately. So if the software raid array is actually
+your root filesystem when you do the kernel install, everything should just work.
+
+----
+CategoryOperatingSystem
