Increasing the size of mdadm RAID1 disks
I started off with 2 existing RAID1 arrays (one for / and one for swap).
cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 sda5[0] sdb5[1]
2094068 blocks super 1.2 [2/2] [UU]
md0 : active raid1 sda1[0] sdb1[1]
10483640 blocks super 1.2 [2/2] [UU]
fdisk -l Disk /dev/sda: 12.9 GB, 12884901888 bytes 255 heads, 63 sectors/track, 1566 cylinders, total 25165824 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000a35cd Device Boot Start End Blocks Id System /dev/sda1 * 2048 20971519 10484736 fd Linux raid autodetect /dev/sda2 20973566 25163775 2095105 5 Extended /dev/sda5 20973568 25163775 2095104 fd Linux raid autodetect Disk /dev/sdb: 12.9 GB, 12884901888 bytes 255 heads, 63 sectors/track, 1566 cylinders, total 25165824 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000b985f Device Boot Start End Blocks Id System /dev/sdb1 * 2048 20971519 10484736 fd Linux raid autodetect /dev/sdb2 20973566 25163775 2095105 5 Extended /dev/sdb5 20973568 25163775 2095104 fd Linux raid autodetect Disk /dev/sdc: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00065756 Device Boot Start End Blocks Id System Disk /dev/sdd: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sdd doesn't contain a valid partition table Disk /dev/md0: 10.7 GB, 10735247360 bytes 2 heads, 4 sectors/track, 2620910 cylinders, total 20967280 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/md0 doesn't contain a valid partition table Disk /dev/md1: 2144 MB, 2144325632 bytes 2 heads, 4 sectors/track, 523517 cylinders, total 4188136 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/md1 doesn't contain a valid partition table
Here’s the file space
df -h Filesystem Size Used Avail Use% Mounted on /dev/md0 9.9G 2.5G 6.9G 27% / udev 997M 8.0K 997M 1% /dev tmpfs 402M 788K 401M 1% /run none 5.0M 0 5.0M 0% /run/lock none 1005M 108K 1005M 1% /run/shm
The next thing to do is get your partitions setup on your replacement disk. Since, I’m growing from 12GB to 20GB in the Virtualbox example, you’ll set that reflected in the partitioning.
fdisk /dev/sdc
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4, default 1): 1
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): 37748736
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
root@mdadm-test:~# fdisk /dev/sdc
Command (m for help): n
Command action
e extended
p primary partition (1-4)
e
Partition number (1-4, default 2): 2
First sector (37748737-41943039, default 37748737):
Using default value 37748737
Last sector, +sectors or +size{K,M,G} (37748737-41943039, default 41943039):
Using default value 41943039
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
root@mdadm-test:~# fdisk /dev/sdc
Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First sector (37750785-41943039, default 37750785):
Using default value 37750785
Last sector, +sectors or +size{K,M,G} (37750785-41943039, default 41943039):
Using default value 41943039
Command (m for help): t
Partition number (1-5): 5
Hex code (type L to list codes): fd
Changed system type of partition 5 to fd (Linux raid autodetect)
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
fdisk /dev/sdd
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4, default 1): 1
First sector (2048-41943039, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): 37748736
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
e
Partition number (1-4, default 2): 2
First sector (37748737-41943039, default 37748737):
Using default value 37748737
Last sector, +sectors or +size{K,M,G} (37748737-41943039, default 41943039):
Using default value 41943039
Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First sector (37750785-41943039, default 37750785):
Using default value 37750785
Last sector, +sectors or +size{K,M,G} (37750785-41943039, default 41943039):
Using default value 41943039
Command (m for help): t
Partition number (1-5): 5
Hex code (type L to list codes): fd
Changed system type of partition 5 to fd (Linux raid autodetect)
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
Here’s the new partitioning…
fdisk -l Disk /dev/sda: 12.9 GB, 12884901888 bytes 255 heads, 63 sectors/track, 1566 cylinders, total 25165824 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000a35cd Device Boot Start End Blocks Id System /dev/sda1 * 2048 20971519 10484736 fd Linux raid autodetect /dev/sda2 20973566 25163775 2095105 5 Extended /dev/sda5 20973568 25163775 2095104 fd Linux raid autodetect Disk /dev/sdb: 12.9 GB, 12884901888 bytes 255 heads, 63 sectors/track, 1566 cylinders, total 25165824 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000b985f Device Boot Start End Blocks Id System /dev/sdb1 * 2048 20971519 10484736 fd Linux raid autodetect /dev/sdb2 20973566 25163775 2095105 5 Extended /dev/sdb5 20973568 25163775 2095104 fd Linux raid autodetect Disk /dev/sdc: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00065756 Device Boot Start End Blocks Id System /dev/sdc1 2048 37748736 18873344+ fd Linux raid autodetect /dev/sdc2 37748737 41943039 2097151+ 5 Extended /dev/sdc5 37750785 41943039 2096127+ fd Linux raid autodetect Disk /dev/sdd: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x36d4ebfb Device Boot Start End Blocks Id System /dev/sdd1 2048 37748736 18873344+ fd Linux raid autodetect /dev/sdd2 37748737 41943039 2097151+ 5 Extended /dev/sdd5 37750785 41943039 2096127+ fd Linux raid autodetect Disk /dev/md0: 10.7 GB, 10735247360 bytes 2 heads, 4 sectors/track, 2620910 cylinders, total 20967280 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/md0 doesn't contain a valid partition table Disk /dev/md1: 2144 MB, 2144325632 bytes 2 heads, 4 sectors/track, 523517 cylinders, total 4188136 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/md1 doesn't contain a valid partition table
Now, we’ll remove one disk at a time, and replace with a new disk. We’re removing both partitions of each disk from each array.
mdadm --manage /dev/md0 --fail /dev/sdb1 mdadm --manage /dev/md0 --remove /dev/sdb1
mdadm --manage /dev/md1 --fail /dev/sdb5 mdadm --manage /dev/md1 --remove /dev/sdb5
Here’s what it will look like after doing that.
cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 sda5[0]
2094068 blocks super 1.2 [2/1] [U_]
md0 : active raid1 sda1[0]
10483640 blocks super 1.2 [2/1] [U_]
Next, let’s add in the 2 new partitions.
mdadm --manage /dev/md0 --add /dev/sdd1 mdadm --manage /dev/md1 --add /dev/sdd5
Wait for both arrays to finish syncing
watch cat /proc/mdstat
Finally, install grub to the new disk
grub-install /dev/sdd
Okay, you’re on the final stretch! Let’s do that with the other disk.
mdadm --manage /dev/md0 --fail /dev/sda1 mdadm --manage /dev/md0 --remove /dev/sda1 mdadm --manage /dev/md1 --fail /dev/sda5 mdadm --manage /dev/md1 --remove /dev/sda5
And add in the replacement
mdadm --manage /dev/md0 --add /dev/sdc1 mdadm --manage /dev/md1 --add /dev/sdc5
Wait for it to finish syncing…
watch cat /proc/mdstat
Install grub on this disk
grub-install /dev/sdc
Next, we need to resize the mdadm array to take advantage of the new space.
mdadm -G /dev/md0 -z max
Here’s the new array’s size.
mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Tue Feb 21 07:29:02 2012
Raid Level : raid1
Array Size : 18872320 (18.00 GiB 19.33 GB)
Used Dev Size : 18872320 (18.00 GiB 19.33 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Tue Feb 21 10:05:40 2012
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Name : mdadm-test:0 (local to host mdadm-test)
UUID : be0e3084:b6d1245a:893001ba:3dbfb1f1
Events : 119
Number Major Minor RaidDevice State
3 8 33 0 active sync /dev/sdc1
2 8 49 1 active sync /dev/sdd1
And finally, resize the filesystem.
resize2fs /dev/md0
Now, reboot and enjoy all of your newfound storage space 🙂
df -h Filesystem Size Used Avail Use% Mounted on /dev/md0 18G 2.6G 15G 15% / udev 997M 8.0K 997M 1% /dev tmpfs 402M 816K 401M 1% /run none 5.0M 0 5.0M 0% /run/lock none 1005M 1.1M 1004M 1% /run/shm
