If you didn't notice in Section 4, this TrinityOS enabled server (Roadrunner) has (7) hard drives and (2) CD-ROMS running on it now. Four IDE HDs are in the main system case and the other (3) SCSI HDs and (1) tape drive is in an old AT-style computer case.
To pull this off, I ordered a SCSI cable that has (2)external HD50pin SCSI-2-Fast connectors on it and 8 internal SCSI 50-pin internal ribbon cable connectors in the middle. I bought this from http://www.corpsys.com [part num: SCSI28] for ~$59. I then used one of my old AT-style cases with its power supply. With all this, I now have a external RAID box! It's no hot-swap cage but it works. Anyway, the following section will tell you how to implement RAID 0 (Striping) in software. Changing the configs to Linear, RAID-1, or RAID-5 won't be hard as long as you can afford the lost capacity or afford the extra disks.
- Download ALL the various version of the RaidTools from the URL in Section 5
The reason to download ALL of the available versions is that I've noticed that some of the versions in the past would NOT compile. Other versions didn't have all the docs, etc. In the past, the Raidtools has been in in a sad state right now but it DOES work nicely once you put it all together.
NOTE:
You will notice that there is both a Software-RAID HOWTO and a Software-RAID-0.4x on the various Linux mirrors. The reason for this is that the 0.4x HOWTO only covered the 2.0.x kernels and was more of a FAQ. The new howto covers the newer 2.2.x Software RAID (via a patch) or the 2.4.x kernels.
Anyway, from here on out, assume I'm using the new Raidtools-0.90 system
- Download and install the newest available kernel found in Section 5 into /usr/src/kernel/linux
- Next, download the newest Raidtools patch for your kernel (URL is in section 5 and also put it in /usr/src/kernel/linux. Don't worry about this code being in the "Alpha" directory, this stuff is VERY stable.
- Apply the patch by running the following comment (for a 2.2.19 kernel): patch -p1 < raid-2.2.19-A1
- Now run "make config" (if you haven't already done this as shown in Section 11)
- Configure the kernel as you normally would but, in the HD hardware support section, enable the following (you can make these modules if you wish but I recommend the monolithic approach):
Multiple devices driver support (CONFIG_BLK_DEV_MD) [Y/n/?] Y
Autodetect RAID partitions (CONFIG_AUTODETECT_RAID) [Y/n/?] Y
Linear (append) mode (CONFIG_MD_LINEAR) [N/y/m/?] N
RAID-0 (striping) mode (CONFIG_MD_STRIPED) [Y/m/n/?] Y
RAID-1 (mirroring) mode (CONFIG_MD_MIRRORING) [Y/m/n/?] Y
RAID-4/RAID-5 mode (CONFIG_MD_RAID5) [Y/m/n/?] Y
Translucent mode (CONFIG_MD_TRANSLUCENT) [Y/m/n/?] N
Hierarchical Storage Management support (CONFIG_MD_HSM) [N/y/m/?] N
Boot support (linear, striped) (CONFIG_MD_BOOT) [Y/n/?] Y
- Now make the kernel as normal with either "make dep; make clean; make bzImage; make modules; make modules_install" or just use TrinityOS's "built-it" script.
- Now, install the kernel into lilo, LOADLIN, etc. and reboot (shown in Section 13 & [ Section 14]).
- Once the box has rebooted, you might not need to compile up the Raidtools-0.90 archive. To verify this, try running "/sbin/mkraid -V". If the program is found and it reports version 0.90.0 then you don't need to do anything. If the program is NOT found, please follow these instructions:
- Uncompress the raidtools-0.90 archive ("tar -xzvf" for .tar.gz or "tar xvIf" for tar.bz2)
- cd into the created directory and run "./configure"
- Then run run "make all" and "make install"
- Hopefully everything went ok
- Now that you have the utilities and your kernel is ready to do, you need to edit your system init files to properly bring up the md0 software-raid service.
!!!NOTE!!! These example configs ASSUME that the partitions to be RAIDed are /dev/hda1 and /dev/sda1. Modify your configs to reflect your own environment!!!
!!!NOTE #2 Some distributions support Software-RAID automatically. To verify if this is so, look in the /etc/rc.d directory with this command:
"rgrep -r -i raid /etc/rc.d"
If anything is found (Redhat and Mandrake have it configured in /etc/rc.d/rc.sysinit), you can just use that setup though they are out of date with the use of "Auto-Dectection" partitions.
- To create a "Auto-Detected" RAID partition, you need to set each one of the HD's RAID partition to type "fd" and NOT the normal ext2, reiserfs, etc.
# /sbin/fdisk /dev/hda The number of cylinders for this disk is set to 1860. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): p Disk /dev/hda: 255 heads, 63 sectors, 1860 cylinders Units = cylinders of 16065 * 512 bytes Device Boot Start End Blocks Id System /dev/hda1 1 1860 14940418+ fd Linux raid autodetect Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks. WARNING: If you have created or modified any DOS 6.x partitions, please see the fdisk manual page for additional information.
- For users that don't want to use Auto-Detect RAID or those users without a RAID-enabled distro, create the following file:
/etc/rc.d/rc.raid
#!/bin/sh
# See how we were called.
case "$1" in
start)
#Start up the RAID subsystem - not needed for auto-detect
/sbin/mkraid /dev/md0
echo "Disks added"
/sbin/raidstart /dev/md0
echo "Raid -RAID0- started on /dev/md0"
;;
manual)
#Start up the RAID subsystem - not needed for auto-detect
/sbin/mkraid /dev/md0
echo "Disks added to /dev/md0"
/sbin/raidstart /dev/md0
echo "Raid RAID0 started on /dev/md0"
/bin/mount -t ext2 /dev/md0 /mnt/raid
;;
stop)
echo "/dev/md0 umounted"
/bin/umount /dev/md0
echo "/dev/md0 stopped"
/sbin/raidstop /dev/md0
;;
*)
echo "Usage: rc.raid {start|stop}"
exit 1
esac
exit 0
Once you have created this script file, make it executable by running "chmod 700 rc.raid"
+++ Older Redhat users ( 5.0-5.2), edit the /etc/rc.d/rc.sysinit (find the following lines and insert the following lines (around line 159):
/etc/rc.d/rc.sysinit
--
if [ -x /sbin/kerneld -a -n "$USEMODULES" ]; then
if [ -f /proc/sys/kernel/modprobe ]; then
# /proc/sys/kernel/modprobe indicates built-in kmod instead
echo "/sbin/modprobe" > /proc/sys/kernel/modprobe
else
/sbin/kerneld
KERNELD=yes
fi
fi
# Start the initialization of the MD0 RAID service
/etc/rc.d/rc.raid start
# Check filesystems
if [ ! -f /fastboot ]; then
echo "Checking filesystems."
fsck -R -A -V -a $fsckoptions
.
.
.
--
+++ Slackware users, edit the /etc/rc.d/rc.S file, find the following text and append the following:
/etc/rc.d/rc.S
--
# remove /etc/mtab* so that mount will create it with a root entry
/bin/rm -f /etc/mtab* /etc/nologin /var/run/utmp \
/etc/shutdownpid /var/run/*.pid
# Start the initialization of the MD0 RAID service
/etc/rc.d/rc.raid start
--
All Distributions:
Though I recommend to read the Software-RAID HOWTO to get all the details, here is an example for:
- A RAID-0 (striped or additive capacity) RAID setup - with (2) HDs on - /dev/hda1 - /dev/sda1
/etc/raidtab
raiddev /dev/md0 #Linear is "linear", RAID0-stripe = "0", RAID1-mirror = "1", RAID5-volume = "5" raid-level 0 #Number of drives you are RAIDing together nr-raid-disks 2 #File system stuff persistent-superblock 1 #Changing this will change performance for your system based on file # sizes, placement, etc. Dont change this unless you plan to reformat # the RAID volume. chunk-size 4 #List and number the drives in the RAID volume device /dev/hda1 raid-disk 0 device /dev/sda1 raid-disk 1
NOTE: There is several raidtab options that can increase performance, etc (stripe size, Inodes..). For now.. I'm just shooting for functionality but the stock performance is pretty good. Please see the Software-RAID howto for more details.
- Ok, so lets start things up MANUALLY to make sure things are ok.
- FIRST, triple check the /etc/raidtab file!! If you have the wrong drive or partition in there, KISS THAT DATA GOODBYE!
- Ok, run the command "/sbin/mkraid /dev/md0". You should see something like the following:
handling MD device /dev/md0 analyzing super-block disk 0: /dev/hda1, 14940418kB, raid superblock at 14940352kB disk 1: /dev/sdb1, 8890352kB, raid superblock at 8890240kB
# cat /proc/mdstat Personalities : [raid0] [raid1] [raid5] [translucent] read_ahead 1024 sectors md0 : active raid0 sdb1[1] hda1[0] 23830592 blocks 4k chunks unused devices: >none<
- Ok, if all is well, just format the /dev/md0 device with your filesystem of choice. For me, I still use EXT2. So, as an example, just run:
mke2fs /dev/md0
NOTE: There is some mke2fs options to increase performance, etc (stripe size, Inodes..). For now.. I'm just shooting for functionality but the stock performance is pretty good. Please see the mke2fs man page for details.
- Once things are formatted, mount it:
mkdir /mnt/raid mount /dev/md0 /mnt/raid
if things went ok, you should have just received the UNIX prompt. So.. check it with the "df" command:
# df
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/sda7 2055600 1470712 480468 75% /
/dev/md0 23456268 20 22264720 0% /mnt/raid
- Ok, so lets make sure this is mounted after reboots, etc. edit the /etc/fstab file to automatically mount this new RAID setup to some mount point. Please note that TrinityOS does NOT cover booting root partitions ( / ) off of Software-RAID setups. Please see the Software-RAID howto on how to do this.
Anyway, here is an example of mounting the RAID setup on /mnt/raid:
#RAID volume mount point FileSys FS options Dump fsck order /dev/md0 /mnt/raid0 ext2 defaults 1 2
- For older setups or people NOT using Auto-Detect RAID:
- Go ahead and type in "/etc/rc.d/rc.raid start"
- If you get any errors about /dev/md0 not existing, run the command "/dev/MAKEDEV md0" and the run the script again. Yes.. use the CAPs.
- Ok, things are cool! Reboot! Make sure things are STILL cool!