Copy Services functions with i5/OS

You can use Copy Services functions with IBM^® i5/OS^® to perform point-in-time copies of your data using the FlashCopy^® function and mirroring your data for disaster recovery using remote mirror and copy functions.

General considerations with i5/OS (prerequisites for Copy Services functions)

Many initial configuration tasks to use i5/OS with the DS6000™ are the same across the various operating systems. However, unlike other operating systems, there are some storage requirements that are unique to i5/OS. For example, LUNs on i5/OS are defined as fixed block storage and only specific LUN sizes are supported, such as 8.5 GB, 17.5 GB, and 35.1 GB. i5/OS LUNs make available a 520-byte block to the host. i5/OS refers to volumes as LUNs.

There are two types of LUN protection: protected and unprotected. In reality, both volume protection types have the same DS6000 internal RAID protection. If you define a LUN as protected, it is protected by the hardware (the DS6000) rather than by i5/OS host-based mirroring. If you define a LUN as unprotected, either the i5/OS or another LUN of equal capacity, either internally or externally mirrors it. The unprotected type is typically used for Load Source Unit mirroring. (Each System i™ or LPAR partition has a special disk called the Load Source Unit. It holds the system’s microcode and is used to reboot the system.) Unless you intend to use i5/OS (host based) mirroring, you should define your LUNs as protected.

In addition, i5/OS supports multipathing, which is part of the base operating system. Multipathing provides redundant path solutions for System i but is only used for external storage like the DS6000. Each connection for a multipath disk unit functions independently. Several connections provide availability by allowing disk storage to be used even if a single path fails.

Some i5/OS considerations are similar to other operating systems regarding how LUNs are defined to volume groups. For example, to access volumes for Copy Services functions with i5/OS, a separate volume group for the target volume IDs is required. Because you do not want to write to the target volumes from the same host while Copy Services functions are running, you might want to put the target volumes in an unassigned volume group until the volumes are needed.

Assuming that you have set up and configured your DS6000 for i5/OS, you can perform FlashCopy and remote mirror and copy operations to create copies of System i disk pools within a single DS6000 or to a distant DS6000 using remote mirror and copy functions. You can save this data and back it up to tape.

You can install and run the DS CLI on i5/OS to allow you to perform Copy Services functions that are supported on the DS6000. You can also use the DS Storage Manager for i5/OS to perform Copy Services functions. The size of the target volumes must be equal the size of the corresponding source volumes. Any mismatch causes the task to fail.

iSeries™ Copy Services Toolkits

The iSeries Copy Services Toolkit allows iSeries users to use the data mirroring capabilities of Copy Services functions on the DS6000. The Toolkit allows iSeries users to take advantage of these functions with minimal downtime of their production system. The Toolkit interfaces with the DS CLI and DS Storage Manager to send Copy Services commands to the DS6000. For more information about the Toolkit, contact your IBM representative.

FlashCopy with the iSeries Copy Services Toolkit: Once configured and implemented, the Toolkit will manage all of the iSeries functions that are necessary to use FlashCopy, which can involve creating a point-in-time version of an independent disk pool called an independent auxiliary storage pool (IASP).
Note: On the iSeries, disk pools are included in auxiliary storage pools (ASPs). Data is scattered across all disks in a given ASP. The first ASP on the system is called the System ASP and includes the operating system. Users can optionally have additional ASPs called user ASPs. These are typically used to hold database journals and savefiles, since these objects need to be separated from the objects they are protecting. The System ASP and all the user ASPs together are called traditional ASPs.
An independent auxiliary storage pool is an independent disk pool. It is a method of configuring multiple disk units into one group. (Disk pool, IASP, and database are sometimes used interchangeably.) An IASP can be varied online or offline together independent of the rest of the storage on a system, including the system ASP, user ASPs, and other independent disk pools. After IASPs are implemented, the FlashCopy operation can be applied to just the IASP, not the entire system.
Remote mirror and copy with the iSeries Copy Services Toolkit: Like the Toolkit for FlashCopy, once configured and implemented, the remote mirror and copy Toolkit manages all of the System i functions that are necessary to allow you generate a second copy of the IASP on another storage unit.

Backup Recovery and Media Services with FlashCopy

Backup, Recovery and Media Services (BRMS) for iSeries is software that helps manage your backups and provides you with an orderly way to retrieve lost or damaged data.

Using BRMS, you can manage your most critical and complex backups simply and easily. You can also recover your system fully in the event of a disaster or failure. In addition to these backup and recovery features, BRMS enables you to track all of your backup media from creation to expiration. You no longer have to keep track of which backup items are on which volumes or worry that you will accidentally write over active data.

The BRMS implementation of FlashCopy provides a way to perform a backup on a system that was copied using the FlashCopy function. BRMS history appears like the backup was performed on the production system.

For more about BRMS, visit the i5/OS Information Center from the IBM Publications Web site using the following URL:

http://publib.boulder.ibm.com/iseries/