IBM Offers HMC-Less iSeries Linux Partitioning
by Timothy Prickett Morgan
In addition to making several storage-related announcements last Tuesday for the iSeries line, IBM has also listened to its customers and developed a new way to create and manage Linux partitions on the iSeries without the need of the Hardware Management Console. The HMC is an external Linux-based management console that controls logical partitions on i5 and p5 Power-based servers. It costs several thousand dollars, and is something of a pain in the neck for small- and medium-sized businesses.
To that end, IBM has created a third way to do Linux partitions, one that gets rid of some of the vulnerabilities in using logical partitions on pre-Virtualization Engine, i5/OS-class iSeries iron even if it does have some restrictions and is not, technically speaking, as resilient or flexible as using the HMC.
When IBM announced logical partitioning in the iSeries many years ago, it started with OS/400 partitions and then eventually added Linux partitions alongside OS/400 partitions. The way partitioning was initially created, the iSeries server was loaded with OS/400, which acted as a host environment for one logical partition per processor in the machine. Over time, IBM boosted partitioning to four logical partitions per processor, then with Linux added 10 partitions per processor. For these partitions, IBM created a virtual Ethernet driver and a virtual SCSI driver, which allowed partitions to access shared network and shared disk resources that were not actually tied to any individual partition. While this setup was way ahead of the competition, disk and I/O were virtualized and could not be tied specifically to any particular logical partition (not a big deal, but something you might want to do) and, more importantly, if anything happened with that primary OS/400 host environment, the guest logical partitions and their own operating system environments would be toast.
With the Virtualization Engine technologies that IBM introduced in the "Squadron" Power5-based servers that are sold as the eServer i5 and eServer p5, an independent virtualization layer was created for the servers that fulfilled the functions of that old host OS/400 primary partition on the iSeries, but eliminated that single point of failure. That hypervisor layer was under the control of an external box, the beloved HMC (yes, that was sarcasm). With this i5/p5 iteration of logical partitioning, specific I/O and network resources can be tied to specific logical partitions (if customers want to do that) and once logical partitions are set up, they pretty much run as set up, even if you shoot the HMC. (Which more than a few people wanted to do last summer, apparently.)
This is a better way to do logical partitioning, unless you happen to be a small business or a reseller servicing one that has to learn how to use the HMC yourself, and then you have to explain to customers they have to spend a few grand to get one and learn how to use it, too, or pay you to make changes to their partitions. This is something of an impediment, particularly for companies that want a mix of i5/OS and Linux on their boxes. If Linux has to be anything on the iSeries, it has to be easy--so easy you don't have to think about using it.
To that end, explains Ian Jarman, the product manager of the iSeries line, IBM has taken a middle road and has created a green-screen tool for i5/OS called the Virtual Partition Manager that will allow customers to create up to four Linux partitions on their iSeries and i5 servers without having to use an HMC. These Linux partitions have to access the network through virtual Ethernet and disk resources through virtual I/O, however. But for small businesses--which is what this offering is aimed at--no one will care about that. This offering is for customers who, for instance, want to add a Linux-based Web server and firewall to their production server. They are going to set up the partitions and the software and then forget about it--except when they need to patch their Linux installations, of course.
While this is not the same thing as offering a PASE-like Linux runtime environment, which I suggested in last week's issue of The Four Hundred (see "The Possibilities of PASE"), that IBM might do to make it simpler and easier for small businesses and their customers to use Linux software on their iSeries machines, the new Virtual Partition Manager is clearly a step in the right direction and is probably a lot smarter and definitely a lot easier to do and support than what I was suggesting. So, kudos once again to IBM Rochester for listening to complaints from the customer base and providing a solution. Virtual Partition Manager is free and comes through a PTF patch that will be available on April 29.
Now, I would not be myself if I let it go at that, as you are all well aware. If IBM can offer a green-screen interface and a manager for customers with a few Linux instances, then it can offer the same thing on big i5 boxes with dozens or hundreds of Linux instances. It can also offer the choice of sticking with virtual Ethernet and virtual SCSI to customers who want to run many OS/400 partitions on an i5 server as well. Given the fact that AIX's I/O structure is a bit different from OS/400, this may not be quite so easy to do for AIX-based logical partitions. It is hard to say, since IBM is pretty vague about what makes OS/400 and AIX similar and different when it comes to I/O, except to say that they are different.
I think that IBM has let the cat out of the bag, and that if it is at all technically possible, the company should let its customers decide if they want virtual I/O and virtual SCSI across OS/400, Linux, and AIX partitions and no HMC, or if they want to use the HMC and tie specific resources to specific partitions.
There is another way out of this, of course. And that is to let someone else manage your partitions by having them log into the HMC port on the server remotely. I am not sure exactly how this can be done without hacking an HMC apart and reverse engineering it to create a secure, remote adapter that would work over a virtual private network to link back to something that looked very much like an HMC to the remote i5box. The HMC settings are just code, after all. I happen to know some people are thinking about such a business, and I also can guess that IBM, which is very big on remote systems management services, must be thinking that there is an opportunity here, too.