Building Disaster Recovery Serviceguard Solutions Using Metrocluster with EMC SRDF

ST LI ST
Standard A N A
Logical T R1 Inv R2 Inv K T R1 Inv R2 Inv RDF Pair
Device Dev E Tracks Tracks S Dev E Tracks Tracks MDAE STATE
-------------------------------- -- ------------------------ ----- ------------
DEV001 80A4 RW 0 0 RW 0340 WD 0 0 A... Consistent
DEV002 80A5 RW 0 0 RW 0341 WD 0 0 A... Consistent
DEV003 80A6 RW 0 0 RW 0342 WD 0 0 A... Consistent
DEV004 80A7 RW 0 0 RW 0343 WD 0 0 A... Consistent
DEV005 80A8 RW 0 0 RW 0344 WD 0 0 A... Consistent
Verifying the EMC Symmetrix configuration
After you complete the procedures in the section “Configuring a device group for
SRDF/asynchronous” (page 17), use the symrdf list command to get a listing of all devices
and their states.
Back up the EMC Solutions Enabler database on each node, so that you do not repeat the
configuration steps if a failure corrupts the database. The EMC Solutions Enabler database is a
binary file located in the directory /var/symapi/db.
Configuring PV links
The examples in the earlier sections describe the use of the vgimport and vgexport commands
with the -s option. In addition, the mk1VGs script uses a -s in the vgexport command, and the
mk2imports script uses a -s in the vgimport command. You can remove the -s option from
both commands if you are using PV links. The -s option to the vgexport command saves the
volume group id (VGID) in the map file, but it does not preserve the order of PV links. To specify
the exact order of PV links, do not use the -s option with vgexport. Instead, the vgimport
command, enter the individual links in the desired order, as in the following example:
# vgimport -v -m mapfilename vgname linkname1 linkname2
NOTE: With the introduction of mass storage stack’s Native Multi-pathing functionality in HP-UX
11i v3, it is not necessary to configure PV links.
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 HP-UX 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
Symmetrix CLI database on each node is already setup, as described in the section, “Preparing
the Cluster for data replication” (page 12).
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.
Setting up M by N configurations 19