TSM server platform selection from DR point of view

IBM Tivoli Storage Manager server and client software is available on many different operating system platforms and can exploit different communications protocols. IBM Tivoli Storage Manager server runs on nine different operating platforms plus the IBM Network Storage Manager (NSM). IBM Tivoli Storage Manager server V5.1 is available for these server platforms, shown in Figure 8-1:

򐂰 AIX

򐂰 Sun Solaris

򐂰 HP-UX

򐂰 Windows NT

򐂰 Windows 2000

򐂰 OS/390

򐂰 z/OS

򐂰 OS/400 (using PASE, expected availability, October 11, 2002)

򐂰 Linux (expected availability, end 2002)

Figure 8-1 Available TSM server platforms

How to choose one TSM server platform over another? Sometimes there will not be a choice because of system availability, historical reasons, or corporate policy.

However if a new server is to be commissioned, then there are certain factors to consider. With only minor differences, a TSM server provides the same

functionality on every platform at the same version and release level. From the TSM client perspective, there is no major difference between any TSM server — they will provide the same services, even for a bare metal recovery. However there are some differences dictated by operating system platform which affect overall costs, administration, and operations. Every platform has different procedures for bare metal recovery or re-installation of the operating system.

Some systems are more scalable or more versatile in terms of peripheral support. If it is desired to use clustered TSM systems or a hot backup system, the question of cost can be important. Table 8-1 summarizes these

considerations.

Table 8-1 TSM server platform consideration

Let’s consider each of these factors in further detail.

Operating system installation and/or restore and operation

If a TSM server is completely destroyed, and there is no hot or warm standby (that is, pre-installed/configured system), re-installation and re-configuration of the operating system on the server will be the first step to site recovery. Since the TSM server must be up first, before any client restores can take place,

commissioning of the server is on the critical path. Therefore, we can speed up the overall process of DR by choosing a TSM server platform which is easy to install or recover.

Installation consists of the hardware platform installation and operating system installation and/or restore. Installing from the CD media will take some time and require certain post-installation configuration steps to bring the TSM server back to working order. This step can be expedited by using available operating system utilities or third-party packages. For example, a TSM server using Windows could be more quickly restored using one of the many third-party “ghosting”

applications. AIX provides the mksysb command for complete backup and restore of the root volume group. The “cleaner” that the TSM server is (that is minimum of extra applications), the easier it will be to recover from scratch. For this reason, we recommend that the TSM server be dedicated for its purpose so that if a new system needs to rebuilt, this will only require operating system re-install, TSM server install, and then use of DRM to re-build the TSM server.

The operation of the TSM server itself is fairly consistent across all platforms — the administrative commands and interfaces are the same. The largest

differences are in attaching and installing devices, and in managing disk volumes for database and log volumes, and disk storage pools. If there are already

Windows

Cost Low Medium Medium to

High

Supported devices Many Many Limited Limited

Capacity Medium Medium to

specific operating system administration skills in the enterprise, these will help to influence the choice of the TSM server platform.

Cost and capacity

Cost is a very relative parameter in an IT solution. A company’s most valuable asset is its data, therefore the first thing to consider when designing a DR solution is the Business Impact Analysis. This will help to understand how much the loss or unavailability of data will cost the enterprise. The real cost of

computer hardware for a TSM server represents only a portion of the total investment required to protect data in an actual IT environment. A much larger fraction is taken up by storage software, administration costs and of course services and education.

The TSM server is architected to manage a virtually unlimited number of clients and amount of data. Various operating system and system platforms however, have different capacities in regard to the CPU power it can deliver to TSM server, the number and size of devices it can attach, and the throughput it can deliver. A TSM server can be installed on a small Windows NT laptop, but this is clearly not a useful production environment. For many companies, the amount of data to be protected is doubling every 18 months. To avoid the disruption of frequent migrations of the TSM server from one system to another, or even upgrading storage devices, it is a good practice to plan for the future today and install capacity for growth. This means choosing a server platform with ample slots, so that more peripherals can be attached, it has a large maximum memory capacity, ability to add processors, and so on. If a server migration becomes necessary, moving to a larger computer of the same operating system type is relatively simple although it will require an outage. It could even be treated as part of DR testing. Moving between different server platforms will require use of the TSM IMPORT and EXPORT commands which is time-consuming as well as labor and resource intensive. Therefore, the decision to change platforms should not be taken lightly.

Supported devices

We have already frequently mentioned the enormous growth in the amount of enterprise data. Storage devices and technologies are being continually

upgraded to keep abreast with this growth. There are a wide variety of supported devices available on the Windows and UNIX platforms, including disk drives, disk arrays, tape drives, optical drives and automated tape libraries. OS/400 and z/OS tend to have a more restricted range. For a list of supported devices on each TSM server platform, see the Web site:

http://www.tivoli.com/support/storage_mgr/devices/all.html

It is also important to carefully check support for SAN-attached devices for using

Recommendations

Choose a TSM server platform where there are suitable skills existing in the company (or where these skills are readily obtainable). Consider ease of operating system recovery in terms of being able to deploy a replacement TSM server as quickly as possible. Ensure that the server system chosen will be able to attach enough storage devices to meet your capacity requirements into the future. Consider how the operating system supports clustering and high availability and any fault-tolerant technology built into the hardware.

In general, most new sites will choose either Windows or one of the UNIX platforms, as these are somewhat easier to administer, and skilled staff are readily available. Companies with significant OS/400 investment and skill will be more comfortable with an OS/400 platform. If you have skilled staff in either Windows or particular UNIX-variants, choose those platforms. For sites with little or no commitment and skills to other platforms, choose AIX. It is easy to install or restore, and robust enough to handle most implementations while remaining relatively cost effective. AIX-based TSM servers are very well supported by IBM in the operating system, TSM and DR Planning. The AIX platform scales from small to very large TSM systems.

Remember that the TSM server is CPU-intensive, I/O-intensive, and

memory-intensive. The amount of data managed is almost invariably going to grow in the first year as new opportunities to use TSM in the enterprise are uncovered. In the majority of cases where a TSM server installation started on hardware shared with other applications, it has been moved to a dedicated machine within the first year. Our recommendation is to dedicate hardware specifically to the TSM server, equip it with enough memory, CPUs, and the appropriate number and type of I/O channels. A typical recommendation is at least 512 MB memory on any platform, Gigabit Ethernet card(s), and at least two SCSI or FC SAN adapters (depending on your storage devices). Make sure that the TSM server hardware has enough free slots for more adapters.