Raid:Manual Rebuild
Raid: Manual Rebuild
SME Servers Raid Options are largely automated, if you built your system with a single hard disk, or have a hard disk failure, simply logon as admin and select Disk Redundancy to add a new drive to your RAID1 array.
HowTo: Manage/Check a RAID1 Array from the command Line
What is the Status of the Array
[root@ ~]# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 sdb2[2] sda2[0]
488279488 blocks [2/1] [U_]
[=>...................] recovery = 6.3% (31179264/488279488) finish=91.3min speed=83358K/sec
md1 : active raid1 sdb1[1] sda1[0]
104320 blocks [2/2] [UU]
unused devices: <none>
Are the Disk Partitioned Correctly ?
Here two disks are partitioned identically
[root@ ~]# fdisk -lu /dev/sda; fdisk -lu /dev/sdb Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Device Boot Start End Blocks Id System /dev/sda1 * 63 208844 104391 fd Linux raid autodetect /dev/sda2 208845 1953520064 976655610 fd Linux raid autodetect Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 63 208844 104391 fd Linux raid autodetect /dev/sdb2 208845 1953520064 976655610 fd Linux raid autodetect
Example : Incorrecty Partitioned 2nd Disk
In this example the partitions are set too close to the start of the disk and there is no room for GRUB to be written, the disk will not boot, there will not be enough room for grub staging
[root@ ~]# fdisk -l /dev/sdb; fdisk -lu /dev/sdb Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 13 104384+ fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sdb2 13 121601 976655647 fd Linux raid autodetect Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 208769 104384+ fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sdb2 208770 1953520063 976655647 fd Linux raid autodetect
message Log showing Grub errors
add_drive_to_raid: Waiting for boot partition to sync before installing grub... add_drive_to_raid: Probing devices to guess BIOS drives. This may take a long time. add_drive_to_raid: add_drive_to_raid: add_drive_to_raid: GNU GRUB version 0.95 (640K lower / 3072K upper memory) add_drive_to_raid: add_drive_to_raid: [ Minimal BASH-like line editing is supported. For the first word, TAB add_drive_to_raid: lists possible command completions. Anywhere else TAB lists the possible add_drive_to_raid: completions of a device/filename.] add_drive_to_raid: grub> device (hd0) /dev/sdb add_drive_to_raid: grub> root (hd0,0) add_drive_to_raid: Filesystem type is ext2fs, partition type 0xfd add_drive_to_raid: grub> setup (hd0) add_drive_to_raid: Checking if "/boot/grub/stage1" exists... no add_drive_to_raid: Checking if "/grub/stage1" exists... yes add_drive_to_raid: Checking if "/grub/stage2" exists... yes add_drive_to_raid: Checking if "/grub/e2fs_stage1_5" exists... yes add_drive_to_raid: Running "embed /grub/e2fs_stage1_5 (hd0)"... failed (this is not fatal) add_drive_to_raid: Running "embed /grub/e2fs_stage1_5 (hd0,0)"... failed (this is not fatal) add_drive_to_raid: Running "install /grub/stage1 (hd0) /grub/stage2 p /grub/grub.conf "... succeeded add_drive_to_raid: Done. add_drive_to_raid: grub> quit
HowTo: Remove a disk from the RAID1 Array from the command Line
Look at the mdstat
[root@ ~]# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 sdb2[1] sda2[0]
488279488 blocks [2/2] [UU]
md1 : active raid1 sdb1[1] sda1[0]
104320 blocks [2/2] [UU]
unused devices: <none>
Fail and remove the disk, sdb in this case
[root@ ~]# mdadm --manage /dev/md2 --fail /dev/sdb2 mdadm: set /dev/sdb2 faulty in /dev/md2 [root@ ~]# mdadm --manage /dev/md2 --remove /dev/sdb2 mdadm: hot removed /dev/sdb2 [root@ ~]# mdadm --manage /dev/md1 --fail /dev/sdb1 mdadm: set /dev/sdb1 faulty in /dev/md1 [root@ ~]# mdadm --manage /dev/md1 --remove /dev/sdb1 mdadm: hot removed /dev/sdb1
Add the partitions back
[root@ ~]# mdadm --manage /dev/md1 --add /dev/sdb1 mdadm: hot added /dev/sdb1 [root@ ~]# mdadm --manage /dev/md2 --add /dev/sdb2 mdadm: hot added /dev/sdb2
The Leadup
I'm not sure if I'm reporting a bug or just some manual maintenance
My Disk didn't respond correctly to the Menu option "Manage Disk Redundancy". I was upgrading the hard disks to 1Gb disks from the 500Gb that came with the Dell server, the new disks were the Seagate 1Tb ST1000340NS, they are a Server Edition disk. It did this on both disks
The Disk was installed as the 2nd Hard Disk during an Upgrade process
It's not fatal, but it did stop the machine from booting on the disk, perhaps that's just not living, therefore not fatal, whatever, it's not terribly useful.
and a look from fdisks view shows
Note the correct partitioning on sda
[root@ ~]# fdisk -lu /dev/sda Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Device Boot Start End Blocks Id System /dev/sda1 * 63 208844 104391 fd Linux raid autodetect /dev/sda2 208845 1953520064 976655610 fd Linux raid autodetect
What has happened here is the disk partition has been written too close to the start of the drive, so the boot record hasn't got enough room for its GRUB staging - if thats the right term.
To correct this, remove the disk from the array, you will need to fail it, then remove it, the repartition and add it back to the array
Here we go lets fix this
Re-Partition, first clean the old partitions
[root@ ~]# fdisk /dev/sdb The number of cylinders for this disk is set to 121601. 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., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): p Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 13 104384+ fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sdb2 13 121601 976655647 fd Linux raid autodetect Command (m for help): d Partition number (1-4): 1 Command (m for help): d Selected partition 2 Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
Then Create the new partitions
Note: change the partitions system id to reflect Linux raid autodetect
[root@ ~]# fdisk /dev/sdb The number of cylinders for this disk is set to 121601. 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., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-121601, default 1): Using default value 1 Last cylinder or +size or +sizeM or +sizeK (1-121601, default 121601): 13 Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 2 First cylinder (14-121601, default 14): Using default value 14 Last cylinder or +size or +sizeM or +sizeK (14-121601, default 121601): Using default value 121601 Command (m for help): m Command action a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only) Command (m for help): a Partition number (1-4): 1 Command (m for help): p Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 13 104391 83 Linux /dev/sdb2 14 121601 976655610 83 Linux Command (m for help): t Partition number (1-4): 1 Hex code (type L to list codes): fd Changed system type of partition 1 to fd (Linux raid autodetect) Command (m for help): t Partition number (1-4): 2 Hex code (type L to list codes): fd Changed system type of partition 2 to fd (Linux raid autodetect) Command (m for help): p Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 13 104391 fd Linux raid autodetect /dev/sdb2 14 121601 976655610 fd Linux raid autodetect Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
and lastly, write the boot sector
[root@ ~]# grub
GNU GRUB version 0.95 (640K lower / 3072K upper memory)
[ Minimal BASH-like line editing is supported. For the first word, TAB
lists possible command completions. Anywhere else TAB lists the possible
completions of a device/filename.]
grub> device (hd0) /dev/sdb
grub> root (hd0,0)
Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd0)
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd0)"... 16 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+16 p (hd0,0)/grub/stage2 /grub/grub.conf"... succeeded
Done.
grub> quit
and then I can use the wiki's proceedure to grow the disk - which is why I am here
David Bray
17 March, 2010