HA (High Availability)¶
This service is packaged inside nethserver-ha
RPM.
The only supported scenario is a two node cluster in active-passive mode.
This package configures:
- a DRBD storage in Primary/Secondary mode, the block device is formatted using ext4 and is mounted only on master node
- Corosync and pacemaker
- A virtual IP on green interface
Architecture¶
Components:
- clustering is done using pacemaker and corosync
- configuration tools are
pcs
andccs
- service data are stored inside a DRBD storage
Constraints¶
- DRBD resource is named
drbd00
- System names are fixed: ns1 for primary node, ns2 for secondary node
Database¶
The ha
key is saved inside the configuration
database and should be
the same on both nodes.
Available options:
ClusterName
: cluster name used for Corosync, if blank a hash of virtual the virtual IP will be usedDrbdDisk
: device where DRBD is stored, default is/dev/VolGroup/lv_drbd
VirtualIP
: virtual ip for clustered servicesVirtualMask
: virtual netmask for clustered services, default is255.255.255.0
STONITH and resource fencing¶
The cluster mys t be configured for both STONITH and resource fencing. Resource fencing is already configured at DRBD level using Corosync Redundant Ring Protocol.
STONITH fencing must be set using pcs
command line tool.