Raid

Software matige RAID

Configureer de Raid voor de dom0 tijdens de installatie van de fysieke host.

De dom0 server zelf

Een een softwarematige RAID bestaat op een dom0 uit meerdere md-devices. Creeer het eerste kleine device 8Gb - 20Gb tijdens de installatie volgens deze stappen:

• in the following menu, scroll to your first disk and hit enter: the partitionier asks you, if you want to create an empty partition table. Say "yes". (Hint: this will erase your existing data, if any.)
• The partitioner is back in the disk overview, scroll one line downwards over the line with "FREE SPACE" and hit enter.
• Create a partition with the size you need, but remember the size and the logical type.
• In the "Partition settings" menu, go to "Use as" and hit enter.
• Change the type to "physical volume for RAID".
• Finish this partition with "Done setting up the partition".
• Create other partitions on the same disk, if you like.
• Now repeat all the steps from the first disk for the second disk.

After this, you should have at least two disks with the same partition schema and all partitions (beside swap) should be marked for RAID use.

• Now look at the first menu entry in the partitioner menu, there is a new line: "Configure software RAID". Go into this menu.
• Answer the question, if you like to write the changes, with "Yes".
• Now pick "Create MD device".
• Use RAID1 and give the number of active and spare devices (2 and 0 in our case).
• In the following menu, select the same device number on the first and second disk and Continue.

Repeat this step for every two devices until you are done. Then use "Finish" from the Multidisk configuration options.

You are back in the partitioner menu and now you see one ore more new partitions named as "Software RAID Device". You can use this partitions like any normal partition and continue installing your system.

Meer info op : http://www.howtoforge.com/software-raid1-grub-boot-debian-etch

5.2.4. Managing RAID devices (RAID-1 and up!!) Setting a disk faulty/failed:

1. mdadm --fail /dev/md0 /dev/hdc1

[Caution] DO NOT run this every on a raid0 or linear device or your data is toasted! Removing a faulty disk from an array:

1. mdadm --remove /dev/md0 /dev/hdc1

Clearing any previous raid info on a disk (eg. reusing a disk from another decommissioned raid array)

1. mdadm --zero-superblock /dev/hdc1

Adding a disk to an array

1. mdadm --add /dev/md0 /dev/hdc1

kopieer partities over volgende drives

De beste manier om identieke partities op raid devices te maken is het kopieren van de partitie tabel over de volgende disk heen:

sfdisk -d /dev/sda | sfdisk /dev/sdb
mdadm -a /dev/md0 /dev/sdb3 /dev/sdd3
mdadm --grow --raid-devices=4 /dev/md0
 623  watch cat /proc/mdstat 
 624  pvscan
 625  mdadm --detail /dev/md0
 626  mdadm --detail /dev/md1
 627  pvscan
 628  pvresize /dev/md1
 629  pvscan

lvm op een software raid

Na de installatie van nuttige software:

root@host:~# apt-get install mdadm raidutils array-info

Configuratie van een nieuw md-device:

root@host:~# cat /proc/mdstat
root@host:~# mdadm -v --create /dev/md0 --level=raid5 --raid-devices=2 /dev/sda5 /dev/sdb5

Volg het proces met:

root@host:~# watch cat /proc/mdstat

root@host:~# pvcreate /dev/md0
root@host:~# pvscan
root@host:~# array-info -v -d /dev/md0
root@host:~# pvdisplay
root@host:~# vgcreate kvm-root /dev/md0

Volg hierna de normale procedure voor het bouwen van een domU.