RAID with Linux

'Real' Hardware RAID

3ware controller

3ware controllers are supported in Vanilla kernel since 'ages'. A command line interface namend tw_cli is available on the download webpage at 3ware.com. A webinterface (providing remote access) is available through the debian-unofficial.org-project:

deb     http://ftp.debian-unofficial.org/debian sarge main contrib non-free restricted
deb-src http://ftp.debian-unofficial.org/debian sarge main contrib non-free restricted

ICP Vortex

ICP Vortex should work as well and provides linux drivers as well, but I've no experience in using them yet...

'Fake' Hardware RAID

That's stuff like Intel ICHx, VIA, Silicon, Adaptec and Promise RAID. Accessing such a RAID is possible with kernel 2.6 using device mapper ('DM') and dmraid (both provided by grml) [kernel 2.4 requires ataraid].

Linux Software RAID

Important: there's a lot of documentation hanging around, describing how to use software raid with raidtools2. raidtools2 is not maintained by its upstream developers anymore and has been replaced by the package mdadm. The last debian package version of raidtools2 shipping the binaries is 1.00.3-17 (available on grml), afterwards it's just a dummy package with dependency on mdadm.

Things to take care of:

• don't take RAID as a backup
• test the setup (remove disk, restore,...) before going productive
• use every disk on its own bus if possible

Installing grml using grml2hd on a bootable SW-RAID ('/' on RAID)

cfdisk /dev/hda                   # select type FD (Linux raid autodetect)
cfdisk /dev/hdc                   # select type FD (Linux raid autodetect)
mdadm --create --verbose /dev/md0 --level=raid1 --raid-devices=2 /dev/hda1 /dev/hdc1 # create raid
mdadm --detail /dev/md0           # show details of raid system
cat /proc/mdstat                  # now wait until raid sync has finished (otherwise performance sucks)
SWRAID='mbr-only' grml2hd /dev/md0 --mbr /dev/md0   # install grml to raid
cat /proc/mdstat                  # again wait until raid sync has finished

Often needed commands

mdadm --detail /dev/md0                        # show details of raid system
cat /proc/mdstat                               # details of mdstat
mdadm --fail /dev/md0 /dev/hdc1                # mark disk as faulty
mdadm -r /dev/md0 /dev/hdc1                    # remove disk from array
mdadm -a /dev/md0 /dev/hdc1                    # integrate disk into array
mdadm --manage --stop /dev/md0                 # stop multidevice
mdadm --assemble /dev/md0 /dev/sda1 /dev/sdb1  # start multidevice

Links

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English

Windows Software RAID

Notice: if you have any chance to boot Windows for accessing the SW-RAID this methode should be prefered. If you can't boot anymore try to boot with a Windows Live-CD (using BartPE). The command line tool diskpart is very useful (start using it via 'select disk $NUMBER', 'detail disk', 'list disk', 'list volume',...).

Links

German

English

Terms

• device-mapper: component of the linux kernel that supports logical volume management (that's the main logical volume manager)
• dmsetup: userspace configuration tool for device-mapper, (let's you) create(s) a device out of a partition, raid,...
• dmraid: based upon device-mapper, searches for 'fake' raids
• dm-crypt and cryptsetup: encryption target of device-mapper, doing block-level encryption using device-mapper
• lvm2: logical volume management (found in linux 2.6 kernels)
• lvm: old, original lvm (found in linux 2.4 kernels)
• evms: Enterprise Volume Management System, handling Software-RAID and logical volume groups
• multipath-tools: