HP Serviceguard Extended Distance Cluster for Linux A.01.
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Table of Contents 1 HP Serviceguard Extended Distance Cluster for Linux A.01.01 Release Notes....................................7 Announcements....................................................................................................................7 What’s In this Version ..........................................................................................................7 Compatibility Information and Installation Requirements.................................................
List of Figures 1-1 4 Package failover sequence...........................................................................................
List of Tables 1-1 1-2 Supported Distance Between Sites..............................................................................10 Failover Sequence........................................................................................................
1 HP Serviceguard Extended Distance Cluster for Linux A.01.01 Release Notes Announcements The HP Serviceguard Extended Distance Cluster (XDC) for Linux is a product that allows an HP Serviceguard for Linux cluster to operate across two separate sites providing disaster tolerance for applications. XDC uses the Linux Multiple Device (MD) driver’s software RAID capability and its associated tool, mdadm, to replicate data across those two sites.
IMPORTANT: When configuring Modular packages with HP Serviceguard A.11.19, the operation_sequence order, which defines the order in which the individual script programs are executed when packages start, must be modified. By default, the XDC script is started only after the pr_cntl script is started. The operation_sequence order must be modified to ensure that the pr_cntl script is started only after the XDC script is started.
• • • Using MD, the disk sets are configured such that data written to one disk or disk set is replicated or mirrored on the other disk or disk set at the other site. As a result, if one disk set is lost, the data is still accessible from the other disk set. The data in the other disk set is always current and up-to-date, ensuring no data loss. You need to create the Multiple Device (MD) only once at the time of configuration. From then onwards, you need to only activate or deactivate the device.
Operating Systems • • • Red Hat 4 U3 or later Red Hat 5 or later Novell SUSE Linux Enterprise Server 10 or later IMPORTANT: The SLES10 release included the kernel 2.6.16.21-0.8. With this kernel version, if you remove a disk from the MD device, it stops responding. If you have SLES10 base version, you must upgrade the kernel to 2.6.16.27-0.6 to avoid this problem.
NOTE: After installing the Extended Distance Cluster software, you need to configure Software RAID. The configuration involves creating a package directory and copying the raid.conf.template file into the relevant package directories. For more information on creating a package and copying the raid.conf.template file, see the HP Serviceguard Extended Distance Cluster for Linux Deployment Guide. Rolling Software Upgrades If you have already deployed XDC A.01.00 with HP Serviceguard for Linux 11.
Figure 1-1 Package failover sequence In this figure, nodes N1 and N2 are in Datacenter 1 at Site 1, while N3 and N4 are in Datacenter 2 in Site 2. In the package configuration file, you need to specify the failover sequence such that N1 of Site 1 is followed by a node in Site 2. In this figure, you need to specify that N1 is followed by N3. Similarly, specify that N2 of Site 1 is followed by N4.
Table 1-2 Failover Sequence (continued) Node Site N1 Site 1 N4 Site 2 N2 Site 1 N3 Site 2 In this table, every node is followed by a node from another site. If this order is not used, then site failures can result in data loss. In the event of a site failure at site S1, if N1 goes down first followed by N2, it results in a package failure. This failure occurs because after N1 fails, the package may failover to N2 if the recommended order of configuration is not specified.
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BUS="scsi", KERNEL="sd*", PROGRAM="/sbin/scsi_id", RESULT="3600508b3009259e05c6fae06fd350002", NAME="%k",SYMLINK="hpdev/mylink-sdb" Then replace the single "=" to double "=" for the parameters BUS, KERNEL, and RESULT to make it work for Red Hat 5.
# RAIDTAB="" # MD (RAID) COMMANDS # Specify the method of activation and deactivation for md. # Leave the default (RAIDSTART="raidstart", "RAIDSTOP="raidstop") if you # want md to be started and stopped with default methods. RAIDSTART="raidstart -c ${RAIDTAB} "RAIDSTOP="raidstop -c ${RAIDTAB}" Software Availability in Native Languages XDC software and documentation is not available in native language versions. 16 HP Serviceguard Extended Distance Cluster for Linux A.01.
