Setting Up Network RAID1 With DRBD On Debian Squeeze
Version 1.0
Author: Falko Timme
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This tutorial shows how to set up network RAID1 with the help of DRBD on two Debian Squeeze systems. DRBD stands for Distributed Replicated Block Device and allows you to mirror block devices over a network. This is useful for high-availability setups (like a HA NFS server) because if one node fails, all data is still available from the other node.
I do not issue any guarantee that this will work for you!
1 Preliminary Note
I will use two servers here (both running Debian Squeeze):
- server1.example.com (IP address 192.168.0.100)
- server2.example.com (IP address: 192.168.0.101)
Both nodes have an unpartitioned second drive (/dev/sdb) with identical size (30GB in this example) that I want to mirror over the network (network RAID1) with the help of DRBD.
It is important that both nodes can resolve each other, either through DNS or through /etc/hosts. If you did not create DNS records for server1.example.com and server2.example.com, you can modify /etc/hosts on both nodes as follows:
server1/server2:
vi /etc/hosts
127.0.0.1 localhost.localdomain localhost 192.168.0.100 server1.example.com server1 192.168.0.101 server2.example.com server2 # The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters |
2 Synchronize Time
server1/server2:
It is very important that both nodes have the same time. Therefore we install the ntp packages:
apt-get install ntp ntpdate
3 Partition /dev/sdb
server1/server2:
Right now, our partitioning looks as follows:
fdisk -l
root@server1:~# fdisk -l
Disk /dev/sda: 32.2 GB, 32212254720 bytes
255 heads, 63 sectors/track, 3916 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00029d5c
Device Boot Start End Blocks Id System
/dev/sda1 * 1 3793 30461952 83 Linux
/dev/sda2 3793 3917 992257 5 Extended
/dev/sda5 3793 3917 992256 82 Linux swap / Solaris
Disk /dev/sdb: 32.2 GB, 32212254720 bytes
255 heads, 63 sectors/track, 3916 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/sdb doesn't contain a valid partition table
root@server1:~#
As you see, /dev/sdb is not partitioned. We change that now and create one big partition on it, /dev/sdb1:
fdisk /dev/sdb
root@server1:~# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x8042e800.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): <-- n
Command action
e extended
p primary partition (1-4)
<-- p
Partition number (1-4): <-- 1
First cylinder (1-3916, default 1): <-- ENTER
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-3916, default 3916): <-- ENTER
Using default value 3916
Command (m for help): <-- t
Selected partition 1
Hex code (type L to list codes): <-- 83
Command (m for help): <-- w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
root@server1:~#
Now run
fdisk -l
again, and you should find /dev/sdb1 in the output:
root@server1:~# fdisk -l
Disk /dev/sda: 32.2 GB, 32212254720 bytes
255 heads, 63 sectors/track, 3916 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00029d5c
Device Boot Start End Blocks Id System
/dev/sda1 * 1 3793 30461952 83 Linux
/dev/sda2 3793 3917 992257 5 Extended
/dev/sda5 3793 3917 992256 82 Linux swap / Solaris
Disk /dev/sdb: 32.2 GB, 32212254720 bytes
255 heads, 63 sectors/track, 3916 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x78f21e78
Device Boot Start End Blocks Id System
/dev/sdb1 1 3916 31455238+ 83 Linux
root@server1:~#
