HP Serviceguard Metrocluster with EMC SRDF for Linux B.01.00.00

Configuring Gatekeeper devices

Gatekeeper device is a special LUN through which host communicates with Symmetrix storage.

These are unique to a Symmetrix unit. They are not replicated across the SRDF link. These devices

are marked GK in the syminq output, and are usually 2880 KB in size. They must be unique per

the Serviceguard package to prevent contention in the Symmetrix when commands are run, such

as two or more packages starting up at the same time.

1. Define at least two gatekeepers per package per node. They will only be available for use

by that node. Each gatekeeper device is configured on different physical links.

# symgate -sid <Symmetrix ID> define dev <Device number>

2. Associate the gatekeeper devices with the Symmetrix device group for that package.

# symgate -sid <Symmetrix ID> -g <Device Group Name> associate dev

3. Define a pool of four or more additional gatekeeper devices that are not associated with any

particular node. The EMC Solutions Enabler switches to an alternate gatekeeper device if the

path to the primary gatekeeper device fails.

Setting up M by N configurations

Metropolitan clusters using EMC SRDF can be built in configurations that use more than two EMC

Symmetrix disk arrays. In such configurations, M arrays located in Data Center A may be connected

to N arrays located in Data Center B. This section describes how to set up an M by N configuration

using EMC Solutions Enabler and Linux commands. It is assumed that either Symmetrix PowerPath

software is installed or RDF-ECA feature of Solutions Enabler is enabled on all the nodes and the

Solutions Enabler database on each node is already setup.

CAUTION: M by N configurations cannot be used with R1/R2 swapping.

Figure 4 depicts a 2 by 2 configuration. Data in this figure are used in the example commands

given in the following sections. This example shows R1 devices at one data center and R2 devices

with Business Continuity Volumes (BCVs) at the other. However, a bidirectional configuration is

also possible, with R1 devices on both sites.

Configuring Gatekeeper devices 15