Difference between revisions of "Talk:Raid"

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from bug 5665
 
The newer e2fs tools are smart enough that if you use the resize2fs tool to do
 
the resizing with a mounted filesystem it will do the same thing ext2online
 
used to do.  They just made it so instead of having two tools you have one
 
smart tool.
 
  
That being said the documentation may need to be updated to handle the sme8
 
case.  However there are a lot of enhanced things you can do with the new tools
 
in 8 that you can't do in 7.  I'd like to see an entire new page explaining how
 
to expand/grow your filesystem on 8 instead of just adding notes for where
 
things are different.
 
 
2011-03-06: added a warning box to RAID1 -> RAID5 conversion: note taken from http://www.arkf.net/blog/?p=47
 
 
 
[[User:Stephdl|Stephdl]] ([[User talk:Stephdl|talk]]) 05:50, 4 February 2013 (MST) i need your help for correcting my english grammar, please be indulgent...
 
i have tested all the command in a virtualbox, it works as expected.
 
 
====Adding another Hard Drive Later (Raid1 array only)====
 
 
ENSURE THAT THE NEW DRIVE IS THE SAME SIZE OR LARGER AS THE CURRENT DRIVE(S)
 
* Shut down the machine
 
* Install drive as master on the second IDE channel (hdc) or the second SATA channel (sda)
 
* Boot up
 
* At the login prompt log on on as admin with the root password to get to the admin console
 
* Go to #5 Manage disk redundancy
 
 
It should show the status and progress if the drives are syncing up. Don't turn off the server until the sync is complete or it will start syncing again from the beginning. When it is done syncing it will show a good working Raid1.
 
 
If the Manage disk redundancy page displays the message "The free disk count must equal one" and "Manual intervention may be required", then you probably have additional hard drives that need to be disconnected while the RAID is set up. An external USB drive will have this effect, and should be unplugged.
 
 
{{Note box| the addition of another drive is restricted to a Raid1 that is degraded, i.e. when the system has been installed with a single drive (/dev/hda and /dev/hdc or their SATA equivalent). The addition of a third drive to a RAID 1 '''(i.e. a spare)''' is not recognized by the system. To add a spare you need to use the management tool '''mdadm''' at the command line}}
 
 
{{Note box|I will assume the system is installed with a Raid1 array functioning with two disks sda and sdb and you want to add another disk sdc as a spare (for adding to the array automatically if one disk of the array fails). This HowTo can be adapted to other types of RAID as long as you want to add a spare disk.}}
 
 
First we need write the partition table from  sda (or sdb) to sdc :
 
 
sfdisk -d /dev/sda > sfdisk_sda.output
 
sfdisk /dev/sdc < sfdisk_sda.output
 
 
Then we need to add the new partitions to the existings arrays :
 
 
mdadm --add /dev/md1 /dev/sdc1
 
mdadm --add /dev/md2 /dev/sdc2
 
 
Verify this with :
 
 
mdadm --detail /dev/md1
 
mdadm --detail /dev/md2
 
 
/dev/md1:
 
        Version : 0.90
 
  Creation Time : Sat Feb  2 22:24:38 2013
 
      Raid Level : raid1
 
      Array Size : 104320 (101.89 MiB 106.82 MB)
 
  Used Dev Size : 104320 (101.89 MiB 106.82 MB)
 
    Raid Devices : 2
 
  Total Devices : 3
 
Preferred Minor : 1
 
    Persistence : Superblock is persistent
 
 
    Update Time : Mon Feb  4 13:28:43 2013
 
          State : clean
 
  Active Devices : 2
 
Working Devices : 3
 
  Failed Devices : 0
 
  Spare Devices : 1
 
 
            UUID : f97a86c5:8bb46daa:6854855e:558a3e16
 
          Events : 0.6
 
 
    Number  Major  Minor  RaidDevice State
 
        0      8        1        0      active sync  /dev/sda1
 
        1      8      17        1      active sync  /dev/sdb1
 
 
        2      8      33        -      spare  /dev/sdc1
 
 
Alternatively you can try this.
 
 
cat /proc/mdstat
 
 
cat /proc/mdstat
 
Personalities : [raid1]
 
md1 : active raid1 sdc1[2](S) sdb1[1] sda1[0]
 
      104320 blocks [2/2] [UU]
 
     
 
md2 : active raid1 sdc2[2](S) sdb2[1] sda2[0]
 
      52323584 blocks [2/2] [UU]
 
 
(S)= Spare
 
(F)= Fail
 
[0]= number of the disk
 
 
You should ensure that grub has been written correctly to the spare disk to ensure that it will boot correctly.
 
 
From within a terminal with the  administrator privileges :
 
 
grub
 
device (hd2) /dev/sdc
 
root (hd2,0)
 
setup (hd2)
 
 
Last of all, try forcing a failure of one of the original two drives and ensure that the server boots, and the RAID rebuilds corectly. You may then have to repeat this exercise to get the drives in the correct order (i.e sda/sdb in the array with sdc as the spare)
 

Latest revision as of 13:31, 15 February 2013