HP OpenView Storage Data Protector A.05.50 SMISA ZDB for HP StorageWorks EVA in HP-UX LVM Mirroring Configuration White Paper Manufacturing Part Number: None (PDF-only) May 2005 © Copyright 2005 Hewlett-Packard Development Company, L.P.
Legal Notices Confidential computer software. Valid license from HP required for possession, use or copying. Consistent with FAR 12.211 and 12.212, Commercial Computer Software, Computer Software Documentation, and Technical Data for Commercial Items are licensed to the U.S. Government under vendor's standard commercial license. The information contained herein is subject to change without notice.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Introduction 1 SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Introduction In this White Paper This white paper describes the extension of SMISA for HP StorageWorks EVA which enables you to perform ZDB (zero downtime backup) in an HP-UX LVM mirroring configuration.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Introduction Terminology BC Business Copy (replication within one EVA array) CA Continuous Access (replication between two EVA arrays) CIMOM CIM Object Manager Disk set A set of physical disks that holds one copy of data in the LVM mirror configuration EVA HP StorageWorks Enterprise Virtual Array IR Instant Recovery Logical Volume Virtual disks created out of Volume Groups Mirror Set A grouping of physical volumes that constitutes one si
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Overview Overview Until now, while performing ZDB in HP-UX LVM mirrored configurations, SMISA considers the whole of a Volume Group as an object-for-backup and replicates all Physical Volumes in that Volume Group. At the same time it ignores the fact that a subset of the Physical Volumes itself holds all the data contained in the entire Volume Group.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Concepts Concepts Prerequisites The following prerequisites are necessary to perform a ZDB session on HP-UX LVM mirroring configurations: • EVA Business Copy licenses available on at least one of the arrays on which the logical volume mirrors will reside. • HP-UX MirrorDisk/UX software license (to enable mirroring functionality on HP-UX LVM) • VCS version 3.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Concepts HP-UX LVM and Mirroring NOTE You need HP MirrorDisk/UX for mirroring. Mirroring is the capability of storing identical copies of data in logical volumes, preferably on separate disks. This redundancy has several advantages: • The system can survive LVM disk crashes if you mirror the root file system and swap. • Valuable data is available on more than one LVM disk thus providing high availability.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Concepts against data loss, even if one of the I/O channels fails. For best performance, group the LVM disks by type. When using physical volume groups, you might also want to use a strictly PVG allocation policy for logical volumes. In a typical LVM mirroring configuration, when the LVM disks are from different arrays, the physical volume groups can be based on the array to which the disks belong.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Concepts SMISA with LVM mirroring functionality expects user LVM configurations to be always PVG-enabled. This means physical volumes are grouped into two or more different Physical Volume Groups. Physical volumes belonging to each of these PVGs are from two or more different EVA arrays. The logical volumes that are to be SMISA backup candidates must be created with the PVG-strict option to ensure the mirrors reside on different data centers.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Concepts Here SMISA will select a mirror and create replicas only for the Storage Volumes found in the PVG. Later these replicas will be presented to the backup host for further backup of the selected backup object. Both PVG-1 and PVG-2 satisfy the mirror set selection rules mentioned above. As SMISA always tries to select a secondary mirror, it chooses PVG-2 over PVG-1 for BC pair replication.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Concepts Configuration 3 In this configuration, some of the secondary mirror members are hosted by the primary mirror array. This violates rule 1, so the secondary mirror cannot be selected for BC pair replication. In such a scenario, SMISA warns the user that it is an unsupported (and unhealthy) configuration, and, to ensure backup objects are still created, selects the primary mirror for BC pair replication.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration Concepts Mirror Selection Algorithm in SMISA 12 Chapter 1
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration New omnirc Variable New omnirc Variable SMISA with LVM mirroring functionality introduces support for a new environment variable that can be set in the file \.omnirc on the application host. Using this variable, you can customize which Physical Volume Group should be used in replication.
SMISA ZDB for EVA in HP-UX LVM Mirroring Configuration New omnirc Variable 14 Chapter 1
