Lecza István (Isu)

My developer life, CV and others...

december 29 03:06:14, 2008

RAID is a method of using multiple hard drives to act as one, reducing the probability of catastrophic data loss in case of drive failure. RAID is implemented in either software (where the operating system knows about both drives and actively maintains both of them) or hardware (where a special controller makes the OS think there's only one drive and maintains the drives 'invisibly').

The RAID software included with current versions of Linux (and Ubuntu) is based on the 'mdadm' driver and works very well, better even than many so-called 'hardware' RAID controllers.

REQUIREMENTS

  1. The "Alternate" install CD for Ubuntu if you're building a desktop system. If you're building a server, the server install CD includes the necessary options. Get Ubuntu.
  2. At least two hard drives, preferably the same mode, size, etc.

PARTITIONING THE DISK

For a 2 hard drive system in RAID 1 configuration. (repeat steps for additional hard drives)

  1. Select "Manual" as your partition method.
  2. Select your 1st hard drive, and agree to "Create a new empty partition table on this device ?"
  3. Repeat step 2 with your 2nd hard drive.
  4. Select the "FREE SPACE" on the 1st drive then select "Create a new partition"
  5. Select the size (suggestion, normally you want a root partition major part of the hard drive and swap which is 1.5 times the amount of ram )
  6. Select Primary, then Beginning.
  7. Select the "Use as:" by default this is "Ext3 journalling file system" we want to change that to "physical volume for RAID"
  8. Select if the partition is the main "/" partition select "bootable flag" and set it to "on"
  9. Select "Done setting up the partition"
  10. Repeat steps 4 to 10 for the 2nd hard drive and the other partitions.

CONFIGURING THE RAID

  1. Once you have complete your partitioning in the main "Partition Disks" page select "Configure Software RAID"
  2. Select "Yes"
  3. Select "Create new MD drive"
  4. Select RAID1, or type of RAID you want (RAID0 RAID1 RAID5)
  5. Number of devices 2 or the amount of hard drives you have
  6. Number of spare devices 0
  7. select which partitions to use. Generally they will be sda1 and sdb1 or hda1 or hdb1. Generally the numbers will match and the different letters are for different hard drives.
  8. At this point the installation may become unresponsive this is the hard drives already syncing. Repeat steps 3 to 7 with each pair of partitions you have created.
  9. Once done, select finish.

FORMATTING

You now have a list of your hard drives and your RAID drives. We will now format and set the mount point for other RAID drives. Treat the RAID drive as a local hard drive and format and mount accordingly

  1. Select Partition.
  2. Go to Use as Select Ext3 for your normal partitions or swap area for your swap partition
  3. If you select Ext 3 then select your mount point if you only have one partition for ext 3 select /
  4. Repeat for each RAID partition. Select "Finish partitioning and write changes to disk"

ADDING GRUB TO 2ND DRIVE

Known problems with GRUB and RAID configurations in anything but RAID 1. GRUB should be installed on all hard drives. If your drives are /sda and /sdb, the first drive will automatically be configured with GRUB but the second drive will not. To add it:

> sudo grub
grub> device (hd1) /dev/sdb
grub> root (hd1,0)
grub> setup (hd1)
grub> quit


You have a RAID 1. Congratulations!

HOZZÁSZÓLÁS, VÉLEMÉNYEK

Welcome ;)
2010-07-16 21:03:00
Many thanks.
2010-07-16 19:10:09
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