Requirements for RDQM HA solution
You must meet a number of requirements before you configure the RDQM high availability (HA) group.
System requirements
- Each node requires a volume group named
drbdpool
. The storage for each replicated data queue manager is allocated as a separate logical volume per queue manager from this volume group. For the best performance, this volume group should be made up of one or more physical volumes that correspond to internal disk drives (preferably SSDs). You can createdrbdpool
before or after you have installed the RDQM HA solution, but you must createdrbdpool
before you actually create any RDQMs. Check your volume group configuration by using the vgs command. The output should be similar to the following:
In particular, check that there is noVG #PV #LV #SN Attr VSize VFree drbdpool 1 9 0 wz--n- <16.00g <7.00g rhel 1 2 0 wz--n- <15.00g 0
c
character in the sixth column of the attributes (that is,wz--nc
). Thec
indicates that clustering is enabled, and if it is you must delete the volume group and recreate it without clustering. - After you have created the
drbdpool
volume group, do nothing else with it. IBM® MQ manages the logical volumes created indrbdpool
, and how and where they are mounted. - Each node requires up to three interfaces that are used for configuring the RDQM support:
- A primary interface for Pacemaker to monitor the HA group.
- An alternate interface for Pacemaker to monitor the HA group.
- An interface for the synchronous data replication, which is known as the replication interface. This should have sufficient bandwidth to support the replication requirements given the expected workload of all of the replicated data queue managers running in the HA group.
You can configure the HA group so that the same IP address is used for all three interfaces, a separate IP address is used for each interface, or the same IP address is used for primary and alternate and a separate IP address for the replication interface.
For maximum fault tolerance, these interfaces should be independent Network Interface Cards (NICs).
- DRBD requires that each node in the HA group has a valid internet host name (the value that is
returned by
uname -n
), as defined by RFC 952 amended by RFC 1123. - If there is a firewall between the nodes in the HA group, then the firewall must allow traffic
between the nodes on a range of ports. A sample script is provided,
/opt/mqm/samp/rdqm/firewalld/configure.sh, that opens up the necessary ports if
you are running the standard firewall in RHEL. You must run the script as
root
. If you are using some other firewall, examine the service definitions/usr/lib/firewalld/services/rdqm*
to see which ports need to be opened. The script adds the following permanent firewallD service rules for DRBD, Pacemaker, and IBM MQ:- MQ_INSTALLATION_PATH/samp/rdqm/firewalld/services/rdqm-drbd.xml allows TCP ports 7000-7100.
- MQ_INSTALLATION_PATH/samp/rdqm/firewalld/services/rdqm-pacemaker.xml allows UDP ports 5404-5407
- MQ_INSTALLATION_PATH/samp/rdqm/firewalld/services/rdqm-mq.xml allows TCP port 1414 (you must edit the script if you require a different port)
-
If the system uses SELinux in Enforcing mode, you must run the
semanage
command:semanage permissive -a drbd_t
Network requirements
It is recommended that you locate the three nodes in the RDQM HA group in the same data center.
- Performance degrades rapidly with increasing latency between data centers. Although IBM will support a latency of up to 5 ms, you might find that your application performance cannot tolerate more than 1 to 2 ms of latency.
- The data sent across the replication link is not subject to any additional encryption beyond that which might be in place from using IBM MQ AMS.
You can optionally configure a floating IP address to enable a client to use the same IP address for a replicated data queue manager (RDQM) regardless of which node in the HA group it is running on. The floating address binds to a named physical interface on the primary node for the RDQM. If the RDQM fails over and a different node becomes the primary, the floating IP is bound to an interface of the same name on the new primary. The physical interfaces on the three nodes must all have the same name, and belong to the same subnet as the floating IP address.
User requirements for configuring the cluster
root
. If you do not want to
configure as root
, you configure as a user in the mqm
group
instead. For a user in the mqm
group to configure the RDQM cluster, you must meet
the following requirements:- The
mqm
user must be able to use sudo to run commands on each of the three servers that make up the RDQM HA group. - If the
mqm
user can use SSH without a password to run commands on each of the three servers that make up the RDQM HA group, then the user needs to run commands on only one of the servers. - The
mqm
user must have the same UID on all three servers. - The
mqm
group must have the same GID on all three servers.
mqm
user can run the following commands with
root
authority:/opt/mqm/bin/crtmqm
/opt/mqm/bin/dltmqm
/opt/mqm/bin/rdqmadm
/opt/mqm/bin/rdqmstatus
User requirements for working with queue managers
To create, delete, or configure replicated data queue managers (RDQMs) you must use a user ID
that belongs to both the mqm
and haclient
groups (the
haclient
group is created during installation of Pacemaker).