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DRBD Quick Command Reference

Martin Loschwitz Edited by Florian Haas

v1.0, Sep 2010

Copyright 2010, 2011 LINBIT HA-Solutions GmbH

Trademark notice

DRBD and LINBIT are trademarks or registered trademarks of LINBIT in Austria, the United States, and othercountries. Other names mentioned in this document may be trademarks or registered trademarks of their respectiveowners.

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1. Initializing a DRBD resource .. ......... ........ ........ ........ ........ ........ ........ ........ ........ ......... ... 12. Frequently used drbdadmcommands ....... ........ ......... ........ ........ ........ ........ ........ ........ 13. Advanced use of drbdadm ....................................................................................... 24. Gathering information on DRBD resources ... .... .... .... .... .... ... .... .... .... .... .... .... ... .... .... .... . 25. DRBD Configuration ............... ........ ........ ........ ........ ........ ........ ......... ........ ........ ........ . 26. Manually resolving a split brain situation .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ... .... .. 37. Interrupting the resynchronisation process ..... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... . 3

8. DRBD Proxy ........ ........ ........ ........ ........ ........ ......... ........ ........ ........ ........ ........ ........ ... 3

The following command reference aims to give you an overview over some of the most importantshell commands for manipulating DRBD resources.

1. Initializing a DRBD resource

In order to create the DRBD meta-data for a given resource, use:

drbdadm create-md

In order to define the Primary node for a freshly created DRBD resource, and at the same time

kick off the initial full synchronization, use thefollowing command:

drbdadm primary --force

Warning

This will cause DRBD to overwriteany data for this resource on the peer node.

2. Frequently useddrbdadmcommands

To enable a DRBD resource on a host, use:

drbdadm up

To disable a DRBD resource, use the following command:

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drbdadm down

To switch a DRBD resource into primary mode, use:

drbdadm primary

To switch a DRBD resource into secondary mode, use:

drbdadm secondary

3. Advanced use ofdrbdadm

To attach a resource to its backing device, use:

drbdadm attach

To detach DRBD from its backing device, use:

drbdadm detach

To enable a DRBD resources network connection, use:

drbdadm connect

To disable a DRBD resources network connection, use:

drbdadm disconnect

To resize a DRBD resource, use:

drbdadm --size=new-size

Warning

Shrinking requires you to follow the right order! See the Resizing resourceschapterin the DRBD Users Guide.

4. Gathering information on DRBD resources

To gather information about existing DRBD resources via the /procpseudo filesystem, use:

cat /proc/drbd

Table 1. Important acronyms in/proc/drbd

acronym meaning

cs connection state

ro role

ds disk state

A more concise overview is provided bydrbd-overview.

5. DRBD Configuration

To set the syncer rate for a specific DRBD resource on the fly, use:

drbdsetup syncer -r

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To see the current live configuration of a resource, use:

drbdsetup show

To adjust the configuration of a resource after having changed the configuration file, use:

drbdadm adjust

6. Manually resolving a split brain situation

On the split brain victim, issue this command:

drbdadm connect --discard-my-data

Afterwards, issue the following command on the split brain survivor:

drbdadm connect

7. Interrupting the resynchronisation processTo pause a currently running resynchronisation process, use:

drbdadm pause-sync

To resume that resynchronisation process later on, use:

drbdadm resume-sync

8. DRBD Proxy

To list connections:

drbd-proxy-ctl -c "list hconnections"

To watch the proxy buffers (run on the Primary node):

watch -n1 'drbd-proxy-ctl -c "show memusage"'

Show currently configured communication paths:

drbd-proxy-ctl -c show