Disk Replication with DRBD - Revision history

Prabuanand: Removed the obsolete notice as the package name has changed from drbd to drbd-utils. Minor formatting

2024-10-10T03:13:03Z

Removed the obsolete notice as the package name has changed from drbd to drbd-utils. Minor formatting

← Older revision		Revision as of 03:13, 10 October 2024
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	~~{{Obsolete\|drbd is no longer available for any supported versions of Alpine Linux}}~~		This tutorial shows how to configure a Distributed Replicated Block Device (DRBD) device on Alpine Linux. It assumes you are familiar with what DRBD is and why you would want to use it. If this is not the case, see [https://linbit.com/drbd/ DRBD home page].

	This tutorial shows how to configure a Distributed Replicated Block Device (DRBD) device on Alpine Linux. It assumes you are familiar with what DRBD is and why you would want to use it. If this is not the case, see ~~the~~ [https://linbit.com/drbd/ DRBD home page].

	You should also be familiar with creating disk partitions, file systems, and logical volumes using command-line tools.		You should also be familiar with creating disk partitions, file systems, and logical volumes using command-line tools.
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	Unless otherwise noted, all procedures will be carried out on both hosts.		Unless otherwise noted, all procedures will be carried out on both hosts.

	= About the Configuration =		== About the Configuration ==
	The examples in this tutorial use two hosts: ''alpine1.domain'' and ''alpine2.domain''. Both are virtual machines. Because the VMs need to communicate with each other, it's important to use a bridged adapter or internal network rather than Network Address Translation (NAT).		The examples in this tutorial use two hosts: ''alpine1.domain'' and ''alpine2.domain''. Both are virtual machines. Because the VMs need to communicate with each other, it's important to use a bridged adapter or internal network rather than Network Address Translation (NAT).

	== Virtual Hardware ==		=== Virtual Hardware ===
	A single CPU with 512M RAM is sufficient. The example uses a single disk, 8G in size.		A single CPU with 512M RAM is sufficient. The example uses a single disk, 8G in size.

	Details of virtual machine hypervisor configuration vary and are not in scope for this document.		Details of virtual machine hypervisor configuration vary and are not in scope for this document.

	== Alpine O.S. ==		=== Alpine O.S. ===
	The hosts are sys installs onto {{path\|/dev/sda}}. The <code>ROOT_SIZE</code> environment variable was used to constrain the partition size to 4G (e.g. export ROOT_SIZE=4096 ; setup-alpine) and leave some free space on the disk. The free space will be used to create a logical volume for DRBD.		The hosts are sys installs onto {{path\|/dev/sda}}. The <code>ROOT_SIZE</code> environment variable was used to constrain the partition size to 4G (e.g. export ROOT_SIZE=4096 ; setup-alpine) and leave some free space on the disk. The free space will be used to create a logical volume for DRBD.

	= Creating a Device for DRBD =		== Creating a Device for DRBD ==
	A DRBD device needs a block device at its foundation. In this tutorial, I'm using a logical volume ({{path\|/dev/vg0/drbd0}}). You can also use a partiton on a regular disk such as {{path\|/dev/sda4}} if you want.		A DRBD device needs a block device at its foundation. In this tutorial, I'm using a logical volume ({{path\|/dev/vg0/drbd0}}). You can also use a partiton on a regular disk such as {{path\|/dev/sda4}} if you want.

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	The logical volume {{path\|/dev/vg0/drbd0}} should be ready for use. Run <code>ls /dev/vg0/drbd0</code> to verify before moving on.		The logical volume {{path\|/dev/vg0/drbd0}} should be ready for use. Run <code>ls /dev/vg0/drbd0</code> to verify before moving on.

	= DRBD Packages and Config Files =		== DRBD Packages and Config Files ==
	Before the DRBD device can be created, you'll need to get some things set up.		Before the DRBD device can be created, you'll need to get some things set up.

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	First, install the packages.		First, install the packages.

	{{cmd\|apk add drbd lsblk}}		{{cmd\|apk add drbd-utils lsblk}}

	Next, you'll need the hostname and IP address for both hosts.		Next, you'll need the hostname and IP address for both hosts.
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	The <code>on alpine1.domain {</code> lines should reflect the names of your hosts. It should match the output of <code>uname -n</code> exactly.		The <code>on alpine1.domain {</code> lines should reflect the names of your hosts. It should match the output of <code>uname -n</code> exactly.

	The <code>address 192.168.0.11:7789;</code> line should reflect the IP address of host alpine1. <code>address 192.168.0.12:7789;</code> should reflect host alpine2. The port numbers do not need to be changed.		The <code>address 192.168.0.11:7789;</code> line should reflect the IP address of host alpine1. <code>address 192.168.0.12:7789;</code> should reflect host alpine2. The port numbers do not need to be changed.

	= The DRBD device =		== The DRBD device ==
	Now that the config files are in place, drbdadm is used to create the DRBD device and make it available for use. It only takes two commands.		Now that the config files are in place, drbdadm is used to create the DRBD device and make it available for use. It only takes two commands.

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	replication:Established peer-disk:Connecting		replication:Established peer-disk:Connecting

	= Primary and Secondary Nodes =		== Primary and Secondary Nodes ==
	In this example, we'll designate the alpine1 host as the primary node and alpine2 as the secondary.		In this example, we'll designate the alpine1 host as the primary node and alpine2 as the secondary.

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	Check the status again with <code>drbdadm status</code> and eventually it will show UpToDate for both disk and replication status.		Check the status again with <code>drbdadm status</code> and eventually it will show UpToDate for both disk and replication status.

	= Using the Device =		== Using the Device ==
	Now that everything is setup, you can use /dev/drbd0 just like any other disk partition. Create a file system, mount it, copy files, etc. From here on out, all commands should be executed on the primary node.		Now that everything is setup, you can use /dev/drbd0 just like any other disk partition. Create a file system, mount it, copy files, etc. From here on out, all commands should be executed on the primary node.

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	Again, this is by design. While it is possible to configure a dual primary system, it is beyond the scope of this document. See https://kb.linbit.com/drbd-9-and-dual-primary for more information.		Again, this is by design. While it is possible to configure a dual primary system, it is beyond the scope of this document. See https://kb.linbit.com/drbd-9-and-dual-primary for more information.

	= When Things Go Wrong =		== When Things Go Wrong ==
	The whole reason for using DRBD is to protect your data in case the primary node fails. So it's a good idea to look at that situation and how you can recover from it.		The whole reason for using DRBD is to protect your data in case the primary node fails. So it's a good idea to look at that situation and how you can recover from it.

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	See the [https://linbit.com/drbd/ LinBit DRBD web site] for more information.		See the [https://linbit.com/drbd/ LinBit DRBD web site] for more information.

	= Important Reminder =		== Important Reminder ==
	DRBD (or any other replicated storage) is not a substitute for a good backup and recovery plan. If your data is important, be sure to [https://en.wikipedia.org/wiki/Backup back it up!]		DRBD (or any other replicated storage) is not a substitute for a good backup and recovery plan. If your data is important, be sure to [https://en.wikipedia.org/wiki/Backup back it up!]

			== See Also ==
			* [https://linbit.com/drbd/ DRBD]

	[[Category:Storage]]		[[Category:Storage]]

Zcrayfish: Mark this article as obsolete: This package is no longer available in current versions of Alpine. Minor formatting, spelling, and grammar improvements as well.

2023-09-06T04:50:06Z

Mark this article as obsolete: This package is no longer available in current versions of Alpine. Minor formatting, spelling, and grammar improvements as well.

← Older revision		Revision as of 04:50, 6 September 2023
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			{{Obsolete\|drbd is no longer available for any supported versions of Alpine Linux}}

	This tutorial shows how to configure a Distributed Replicated Block Device (DRBD) device on Alpine Linux. It assumes you are familiar with what DRBD is and why you would want to use it. If this is not the case, see the [https://linbit.com/drbd/ DRBD home page].		This tutorial shows how to configure a Distributed Replicated Block Device (DRBD) device on Alpine Linux. It assumes you are familiar with what DRBD is and why you would want to use it. If this is not the case, see the [https://linbit.com/drbd/ DRBD home page].

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	= About the Configuration =		= About the Configuration =
	The examples in this tutorial use two hosts: ''alpine1.domain'' and ''alpine2.domain''. Both are virtual machines. Because the VMs need to communicate with each other, it's important to use a bridged adapter or internal network rather than Network ~~Adress~~ Translation (NAT).		The examples in this tutorial use two hosts: ''alpine1.domain'' and ''alpine2.domain''. Both are virtual machines. Because the VMs need to communicate with each other, it's important to use a bridged adapter or internal network rather than Network Address Translation (NAT).

	== Virtual Hardware ==		== Virtual Hardware ==
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	== Alpine O.S. ==		== Alpine O.S. ==
	The hosts are sys installs onto /dev/sda. The ROOT_SIZE environment variable was used to constrain the partition size to 4G (e.g. export ROOT_SIZE=4096 ; setup-alpine) and leave some free space on the disk. The free space will be used to create a logical volume for DRBD.		The hosts are sys installs onto {{path\|/dev/sda}}. The <code>ROOT_SIZE</code> environment variable was used to constrain the partition size to 4G (e.g. export ROOT_SIZE=4096 ; setup-alpine) and leave some free space on the disk. The free space will be used to create a logical volume for DRBD.

	= Creating a Device for DRBD =		= Creating a Device for DRBD =
	A DRBD device needs a block device at its foundation. In this tutorial, I'm using a logical volume (/dev/vg0/drbd0). You can also use a regular ~~scsi~~ disk ~~device like~~ /dev/sda4 if you want.		A DRBD device needs a block device at its foundation. In this tutorial, I'm using a logical volume ({{path\|/dev/vg0/drbd0}}). You can also use a partiton on a regular disk such as {{path\|/dev/sda4}} if you want.

	The process to create the device requires you to perform these steps:		The process to create the device requires you to perform these steps:
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	# Install necessary packages		# Install necessary packages
	# Create a partition for LVM		# Create a partition for LVM
	# Create the ~~phyisical~~ volume, volume group, and logical volume		# Create the physical volume, volume group, and logical volume
	# Configure LVM to start when the system boots.		# Configure LVM to start when the system boots.

	The commands you'll run to install packages and create the partition look like this:		The commands you'll run to install packages and create the partition look like this:

	apk add cfdisk lvm2		{{cmd\|apk add cfdisk lvm2
	cfdisk /dev/sda		cfdisk /dev/sda}}

	You'll need to create a partition in the free space area of the drive, change the type to Linux LVM, write, and quit.		You'll need to create a partition in the free space area of the drive, change the type to Linux LVM, write, and quit.

	Once that's done, you can go ahead with the logical volume. Assuming /dev/sda4 is the partition for LVM, the commands will look like this:		Once that's done, you can go ahead with the logical volume. Assuming {{path\|/dev/sda4}} is the partition for LVM, the commands will look like this:

	pvcreate /dev/sda4		{{cmd\|pvcreate /dev/sda4
	vgcreate vg0 /dev/sda4		vgcreate vg0 /dev/sda4
	lvcreate -n drbd0 -L 1G vg0		lvcreate -n drbd0 -L 1G vg0
	rc-update add lvm boot		rc-update add lvm boot}}

	The logical volume /dev/vg0/drbd0 should be ready for use. Run <code>ls /dev/vg0/drbd0</code> to verify before moving on.		The logical volume {{path\|/dev/vg0/drbd0}} should be ready for use. Run <code>ls /dev/vg0/drbd0</code> to verify before moving on.

	= DRBD Packages and Config Files =		= DRBD Packages and Config Files =
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	First, install the packages.		First, install the packages.

	apk add drbd lsblk		{{cmd\|apk add drbd lsblk}}

	Next, you'll need the hostname and IP address for both hosts.		Next, you'll need the hostname and IP address for both hosts.

	uname -n		{{cmd\|uname -n
	ifconfig eth0		ifconfig eth0}}

	Finally, you can create the DRBD resource configuration file. In this example it's called drbd0.res and it resides in the /etc/drbd.d/ directory. This file needs to be created on both hosts.		Finally, you can create the DRBD resource configuration file. In this example it's called drbd0.res and it resides in the {{path\|/etc/drbd.d/}} directory. This file needs to be created on both hosts.

	The contents will look similar to this example:		The contents will look similar to this example:
			{{cat\|/etc/drbd.d/drbd0.res\|<nowiki>
	resource drbd0 {		resource drbd0 {
	device minor 0;		device minor 0;
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	address 192.168.0.12:7789;		address 192.168.0.12:7789;
	}		}
	}		}</nowiki>}}

	The line <code>disk /dev/vg0/drbd0;</code> should reflect the name of the device you're using. If you're not using a logical volume, it might be something like <code>disk /dev/sda4;</code>		The line <code>disk /dev/vg0/drbd0;</code> should reflect the name of the device you're using. If you're not using a logical volume, it might be something like <code>disk /dev/sda4;</code>
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	Now that the config files are in place, drbdadm is used to create the DRBD device and make it available for use. It only takes two commands.		Now that the config files are in place, drbdadm is used to create the DRBD device and make it available for use. It only takes two commands.

	drbdadm create-md drbd0		{{cmd\|drbdadm create-md drbd0
	drbdadm up drbd0		drbdadm up drbd0}}

	You can use <code>lsblk</code> and <code>drbdadm status</code> to verify your success.		You can use <code>lsblk</code> and <code>drbdadm status</code> to verify your success.
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	# Mount drbd0's file system on alpine2.		# Mount drbd0's file system on alpine2.

	But before that, create a test file under /mnt on alpine1. Anything is fine, it's just to verify the process works.		But before that, create a test file under {{path\|/mnt}} on alpine1. Anything is fine, it's just to verify the process works.

	Then, when alpine1 is powered off, run the drbdadm command to make alpine2 the primary:		Then, when alpine1 is powered off, run the drbdadm command to make alpine2 the primary:
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	peer connection:Connecting		peer connection:Connecting

	The real proof is in the file system and the test file you created. To verify, mount alpine2's /dev/drbd0 on /mnt and see what it contains.		The real proof is in the file system and the test file you created. To verify, mount alpine2's {{path\|/dev/drbd0}} on {{path\|/mnt}} and see what it contains.

	alpine2:~# e2fsck /dev/drbd0		alpine2:~# e2fsck /dev/drbd0

Dhorton at 14:34, 4 May 2022

2022-05-04T14:34:49Z

← Older revision		Revision as of 14:34, 4 May 2022
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	~~{{Draft}}~~

	This tutorial shows how to configure a Distributed Replicated Block Device (DRBD) device on Alpine Linux. It assumes you are familiar with what DRBD is and why you would want to use it. If this is not the case, see the [https://linbit.com/drbd/ DRBD home page].		This tutorial shows how to configure a Distributed Replicated Block Device (DRBD) device on Alpine Linux. It assumes you are familiar with what DRBD is and why you would want to use it. If this is not the case, see the [https://linbit.com/drbd/ DRBD home page].

Dhorton at 21:44, 29 April 2022

2022-04-29T21:44:41Z

← Older revision		Revision as of 21:44, 29 April 2022
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	The <code>address 192.168.0.11:7789;</code> line should reflect the IP address of host alpine1. <code>address 192.168.0.12:7789;</code> should reflect host alpine2. The port numbers do not need to be changed.		The <code>address 192.168.0.11:7789;</code> line should reflect the IP address of host alpine1. <code>address 192.168.0.12:7789;</code> should reflect host alpine2. The port numbers do not need to be changed.

	== The DRBD device ==		= The DRBD device =
	Now that the config files are in place, drbdadm is used to create the DRBD device and make it available for use. It only takes two commands.		Now that the config files are in place, drbdadm is used to create the DRBD device and make it available for use. It only takes two commands.

Dhorton: Complete rewrite. Original page was sparse and several years old.

2022-04-29T21:43:27Z

Complete rewrite. Original page was sparse and several years old.

Show changes

Larena: /* Disk Replication with DRBD */

2021-10-04T12:30:24Z

Disk Replication with DRBD

← Older revision		Revision as of 12:30, 4 October 2021
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	== Disk Replication with DRBD ==		== Disk Replication with DRBD ==
	~~DRBD support is present only in SCST version of Alpine. At the time of this writing DRBD tools are currently in edge (testing).~~

	#apk add drbd		#apk add drbd

Bt129: /* Disk Replication with DRBD */

2021-07-05T04:44:49Z

Disk Replication with DRBD

← Older revision		Revision as of 04:44, 5 July 2021
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	It is recommended to have a dedicated heartbeat interface for DRBD where replication occurs.		It is recommended to have a dedicated heartbeat interface for DRBD where replication occurs.

	Create DRBD device and bring it up on '''both nodes''':		Create the DRBD device and bring it up on '''both nodes''':

	#drbdadm create-md r0		#drbdadm create-md r0
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	#drbdadm -- --overwrite-data-of-peer primary r0		#drbdadm -- --overwrite-data-of-peer primary r0

	If you want to temporarily speed up replication run (e.g. 1G):		If you want to temporarily speed up replication, run (e.g. 1G):

	#drbdsetup /dev/drbd1 syncer -r 1G		#drbdsetup /dev/drbd1 syncer -r 1G

Dubiousjim: Category:Storage

2012-03-12T08:18:11Z

Category:Storage

← Older revision		Revision as of 08:18, 12 March 2012
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	#cat /proc/drbd		#cat /proc/drbd

			[[Category:Storage]]

Larena: first writing

2011-11-08T09:52:53Z

first writing

New page

{{Draft}}

== Disk Replication with DRBD ==
DRBD support is present only in SCST version of Alpine. At the time of this writing DRBD tools are currently in edge (testing).

#apk add drbd

Load DRBD kernel driver:

#modprobe drbd

Sample DRBD configuration in /etc/drbd.d/r0.res (resource 0):

resource r0 {
device /dev/drbd1;
disk /dev/md0;
meta-disk internal;
on host1 {
address 192.168.0.1:7789;
}
on host2 {
address 192.168.0.2:7789;
}
}

It is recommended to have a dedicated heartbeat interface for DRBD where replication occurs.

Create DRBD device and bring it up on '''both nodes''':

#drbdadm create-md r0
#drbdadm up r0

On primary node start replication:

#drbdadm -- --overwrite-data-of-peer primary r0

If you want to temporarily speed up replication run (e.g. 1G):

#drbdsetup /dev/drbd1 syncer -r 1G

Control replication status:

#cat /proc/drbd