DRBD SSH
Overview
DRBD (Distributed Replicated Block Device) is a distributed storage architecture for GNU/Linux, allowing the replication of block devices (disks, partitions, logical volumes etc.) between servers. DRBD is free software, but support exists. DRBD consists of a kernel module, administration tools in user space as well as shell scripts.
Plugin-Pack Assets
Monitored Objects
- DRBD replication including roles, peers, devices
Collected Metrics
More information about collected metrics is available in the official DRBD documentation : https://www.linbit.com/drbd-user-guide/drbd-guide-9_0-en/
| Metric name | Description | Unit |
|---|---|---|
| disk-status | Disk status | |
| peer-connection-status | Peer connection status | |
| peer-device-replication-status | Peer device replication status | |
| peer-device-disk-status | Peer device disk status | |
| resources.total.count | Total number of resources | count |
| disk.data.read.bytespersecond | Disk data read | B/s |
| disk.data.written.bytespersecond | Disk data written | B/s |
| peer.traffic.in.bitspersecond | Peer traffic in | b/s |
| peer.traffic.out.bitspersecond | Peer traffic out | b/s |
Prerequisites
A number of distributions provide DRBD, including pre-built binary packages. Support for these builds, if any, is being provided by the associated distribution vendor. Their release cycle may lag behind DRBD source releases.
More information is available on the official documentation of DRBD : https://www.linbit.com/drbd-user-guide/drbd-guide-9_0-en/#ch-install-packages
The centreon-engine user performs a SSH connection to a remote system user. This user must have enough privileges to run /usr/bin/drbdsetup command.
Setup
- Install the Centreon Plugin on every Poller monitoring DRBD resources:
yum install centreon-plugin-Applications-Drbd-Ssh.noarch
- On the Centreon Web interface in "Configuration > Plugin packs > Manager", install the DRBD SSH Plugin-Pack
- Install the Centreon Plugin on every Poller monitoring DRBD resources:
yum install centreon-plugin-Applications-Drbd-Ssh.noarch
- On the Centreon Central server, install the Centreon Plugin-Pack from the RPM:
yum install ccentreon-pack-applications-drbd-ssh.noarch
- On the Centreon Web interface in "Configuration > Plugin packs > Manager", install the DRBD SSH Plugin-Pack
Configuration
Adding a Host into Centreon, link it to the Template named App-Drbd-SSH-custom. Once the Template set, you have to set values according to the chosen SSH backend. 3 SSH backends are available to connect to the remote server: sshcli, plink and libssh which are detailed below.
| Mandatory | Name | Description |
|---|---|---|
| X | SSHBACKEND | Name of the backend: sshcli |
| X | SSHUSERNAME | By default, it uses the user running process centengine on your Poller |
| SSHPASSWORD | Cannot be used with backend. Only ssh key authentication | |
| SSHPORT | By default: 22 | |
| SSHEXTRAOPTIONS | Customize it with your own if needed. E.g.: --ssh-priv-key=/user/.ssh/id_rsa |
Warning With that backend, you have to validate the target server fingerprint manually (with the SSHUSERNAME used).
| Mandatory | Name | Description |
|---|---|---|
| X | SSHBACKEND | Name of the backend: plink |
| X | SSHUSERNAME | By default, it uses the user running process centengine on your Poller |
| SSHPASSWORD | Can be used. If not set, SSH key authentication is used | |
| SSHPORT | By default: 22 | |
| SSHEXTRAOPTIONS | Customize it with your own if needed. E.g.: --ssh-priv-key=/user/.ssh/id_rsa |
Warning With that backend, you have to validate the target server fingerprint manually (with the SSHUSERNAME used).
| Mandatory | Name | Description |
|---|---|---|
| X | SSHBACKEND | Name of the backend: libssh |
| X | SSHUSERNAME | By default, it uses the user running process centengine on your Poller |
| SSHPASSWORD | Can be used. If not set, SSH key authentication is used | |
| SSHPORT | By default: 22 | |
| SSHEXTRAOPTIONS | Customize it with your own if needed. E.g.: --ssh-priv-key=/user/.ssh/id_rsa |
With that backend, you do not have to validate the target server fingerprint manually.
FAQ
How to check in the CLI that the configuration is OK and what are the main options for ?
Once the Plugin installed, log into your Poller using the centreon-engine user account and test by running the following command :
/usr/lib/centreon/plugins/centreon_drbd_ssh.pl \
--plugin=apps::drbd::local::plugin.pm \
--mode=resources \
--hostname=10.30.2.81 \
--ssh-username=centreon \
--ssh-password=centreon-password \
--ssh-backend=libssh \
--legacy-proc \
--verbose
Which output something similar to:
OK: total resources: 9 - All drbd resources are ok
| 'resources.total.count'=9;;;0; '0#disk.data.read.bytespersecond'=0B/s;;;0; '0#disk.data.written.bytespersecond'=0B/s;;;0; '0~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'0~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '1#disk.data.read.bytespersecond'=0B/s;;;0; '1#disk.data.written.bytespersecond'=0B/s;;;0; '1~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'1~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '2#disk.data.read.bytespersecond'=0B/s;;;0; '2#disk.data.written.bytespersecond'=0B/s;;;0; '2~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'2~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '3#disk.data.read.bytespersecond'=0B/s;;;0; '3#disk.data.written.bytespersecond'=0B/s;;;0; '3~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'3~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '4#disk.data.read.bytespersecond'=0B/s;;;0; '4#disk.data.written.bytespersecond'=0B/s;;;0; '4~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'4~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '5#disk.data.read.bytespersecond'=0B/s;;;0; '5#disk.data.written.bytespersecond'=0B/s;;;0; '5~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'5~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '6#disk.data.read.bytespersecond'=0B/s;;;0; '6#disk.data.written.bytespersecond'=0B/s;;;0; '6~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'6~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '7#disk.data.read.bytespersecond'=0B/s;;;0; '7#disk.data.written.bytespersecond'=0B/s;;;0; '7~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'7~0#peer.traffic.out.bitspersecond'=0b/s;;;0; '8#disk.data.read.bytespersecond'=0B/s;;;0; '8#disk.data.written.bytespersecond'=0B/s;;;0; '8~0#peer.traffic.in.bitspersecond'=0b/s;;;0;
'8~0#peer.traffic.out.bitspersecond'=0b/s;;;0;
The command above gets the status of resources DRBD SSH (--mode=resources).
It uses a SSH username centreon (--ssh-username=centreon), a SSH password centreon-password (--ssh-password='centreon-password'),
uses a SSH backend libssh (--ssh-backend='libssh') and it connects to the host 10.30.2.81 (--hostname=10.30.2.81)
on the SSH default port 22 (--ssh-port=22).
The legacy-proc (--legacy-proc) option allows you to use the old proc file (/proc/drbd). This makes it possible to use a version prior to version 9.
All the options that can be used with this plugin can be found over the --help options:
/usr/lib/centreon/plugins/centreon_drbd_ssh.pl \
--plugin=apps::drbd::local::plugin.pm \
--mode=resources --help
I have that error message: UNKNOWN: Command error: Host key verification failed.. What does it mean ?
It means you haven't manually validated the target server fingerprint with ssh or plink on the Centreon Poller.