Users running AIX and Linux applications can migrate entire partitions and hosted applications from one physical server to another in a matter of seconds.
One of the success stories at IBM during the past couple years has been the popularity of PowerVM, and one of the most intriguing features of PowerVM is Live Partition Mobility. Still available only in the PowerVM Enterprise Edition, Live Partition Mobility allows the user to migrate an active or inactive AIX or Linux logical partition from one system to another—without disrupting the running applications or users residing on them.
To a system administrator, having the ability to bring down a server to perform maintenance and then reactivate it without interrupting users or the applications in use is tantamount to finding the Holy Grail in the data center.
Earlier this week, IBM announced a series of new POWER7 servers, including the big IBM Power 795, and four smaller servers for SMBs: the IBM Power 710, 720, 730 and 740 Express. During the course of a press briefing, Steve Sibley, manager, IBM Power Systems servers offering management, mentioned to me that some 80 percent of IBM's customers today that purchase POWER7 servers also get one version or another of PowerVM.
There are three versions of PowerVM: Express, Standard, and Enterprise editions. The one with the most features, of course, is the Enterprise Edition. Not only does it offer Live Partition Mobility, but it also gives you Active Memory Sharing—the ability to share memory among logical partitions in a shared memory pool. Most people are buying either the Standard or Enterprise editions of PowerVM, Sibley said, but there is little difference between the two as far as I can tell. Both offer micro-partitioning technology, Virtual I/O Server, the Integrated Virtualization Manager, and Lx86. Lx86 allows you to run Linux applications designed for the x86 processor on a POWER chip, giving IBM customers access to a large library of existing Linux applications.
Live Partition Mobility, however, is a feature that excites IT people for the freedom it promises. Unfortunately, it's not currently available for IBM i servers, only AIX and Linux. We don't know if it's in the future for IBM i or not. However, new customers who are porting their Sun (Oracle) or HP UNIX applications over to AIX on POWER7 will have it available to them if they so choose. You must be running at least a POWER6 processor-based machine (or POWER7). IBM i users have had Virtual Partition Manager for some time, which allows the user to create and manage at least one IBM i partition and up to four Linux logical partitions on a single server on models that don't require a Hardware Management Console (HMC). Live Partition Mobility can be combined with other virtualization technologies, including logical partitions, Live Workload Partitions introduced in AIX 6.1, and the SAN Volume Controller.
How to implement Live Partition Mobility and what it can be used for is the subject of a 300-page IBM Redbook titled, appropriately, IBM PowerVM Live Partition Mobility, but we can give you an introduction to this impressive technology. According to a summary on the subject released last April, users will need the HMC (V7 with various releases, depending on hardware, but starting with R3.4 or R710 for POWER7), Integrated Virtualization Manager (provided by the Virtual I/O Server V220.127.116.11 or higher on both source and destination), and PowerVM Enterprise Edition on both the source and destination systems. Both systems need to be at firmware level 01Ex320, where x is an S for BladeCenter, an L for entry servers, an M for midrange servers, or an H for enterprise servers. There are firmware compatibility and upgrade issues, and the firmware migration matrix, as of last April, can be found here.
There are minimum requirements for the operating systems as well, which very generally are AIX5L V5.3 Technology Level 7 or AIX 5.3 Technology Level 09 with Service Pack 7 for POWER7 servers; AIX V 6.1 or 6.1 Technology Level 02 and Service Pack 8 or later; Red Hat Enterprise Linux V5 Update 1; or SUSE Linux Enterprise Server 10 (SLES 10) Service Pack 1. The operating system running in the mobile partition has to be AIX or Linux. As mentioned earlier, a Virtual I/O Server logical partition or a logical partition running IBM i cannot be migrated. But a system is capable of being either the source or destination of a migration if it contains the necessary processor hardware to support it. There are numerous fixes that also affect LPM. See Neil Koropoff's summary, Live Partition Mobility (LPM) Nutshell, for details.
The PowerVM Enterprise Edition requires an activation code to enable the hardware feature, and when you order the feature, the firmware is activated at the factory. If you order the feature separately from the server, however, you can enter the code using the HMC or the Virtualization Manager, and it's different from that of the Standard Edition.
So, the point of those references, frankly, is to let readers know there are a number of pre-conditions to setting up and using Live Partition Mobility. The benefits, however, could be well worth it in the right environment. Not only can you migrate entire running AIX and Linux partitions and hosted applications from one physical server to another without disruption, but you can also quickly rebalance loads across systems. If you only need a single partition migration, there is actually a migration wizard that will guide you through it. Imagine performing such a migration in a matter of seconds. You can do with Live Partition Mobility.
As the authors of the Redbook point out, even small servers today often host many logical partitions, and as the number of these partitions increases, finding a window to do system maintenance that doesn't affect someone becomes increasingly difficult. And if you happen to be bound by a service-level agreement, Life Partition Mobility can help you meet your commitments by keeping applications up and running despite the occasional hardware maintenance job.
Given the benefits that Live Partition Mobility can provide (not to mention Active Memory Sharing, which we will discuss in a future issue), it seems clear why the Enterprise Edition of PowerVM has such broad appeal to today's Power Systems UNIX and Linux customers.