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The Mainframe Still Lives!
coondoggie passed us a NetworkWorld blog post about the incredible rock-em-sock-em mainframe. Knocked frequently in recent years, the site notes that IBM's workhorse continues to do important work in a number of enterprise environments. "While there are some out there who'd like to see its demise, a true threat to the Big Iron has never really amounted to much. Even today, the proponents of commodity boxes offering less expensive x86/x64 or RISC technologies say the mainframe is doomed. But the facts say otherwise. For example, IBM recently said the mainframe has achieved three consecutive quarters of growth, marked by new customers choosing the platform for the first time and existing customers adding new workloads, such as Linux and Java applications."
Hardware quality is the key here. It may not matter, if the application is even 30% faster on x86. But if the motherboard is buggy, or the parallel port is flaky, or cable can fluctuate, or the video card can get loose (early AGPs anyone?) — it is death. Even if the probability of it ever happening is very low, the costs will be devastating. Thus the expectation (probabilty times cost) of the loss is still lower than the cost.
I've heard of machines, where the CPUs or memory can be replaced without shutting down — 15 years ago (Sequoia)... Meanwhile, some controllers and OSes still don't fully support hard-disk replacement, or even network cable unplugging — today...
In Soviet Washington the swamp drains you.
FYI...AS/400 is NOT a mainframe
Mainframes have been running VMs for years.
Years? More like decades. IBM more or less invented virtualization back in the 60s for the System/390, and it lives on today as z/VM.
So why not upgrade the OS to a supported version? If your hardware is recently purchased/new, it probably cannot even run too many releases of unsupported operating systems anyway. And all the latest IBM operating system versions run on all the mainframe models stretching back to the end of 2000 (three generations). IBM always has a lot of overlap.
If you have z/OS V1.x, the upgrade to 1.8 or (soon) 1.9 is free. If you have OS/390 still -- hard to imagine on recently purchased/new hardware since it doesn't run on the z9 anyway -- the upgrade to z/OS is probably better than free (i.e. you typically save money), and you usually save money on the other software that runs on z/OS. (z/OS introduced subcapacity licensing.) And you have a full year when you can run both on the same system for no additional charge to get the migration done.
An OS upgrade is extremely unlikely to break any applications. There's 40+ year old code that's still running, right along with 64-bit Java code written an hour ago. Your 17 to 18 year old code should be perfectly happy on the new OS. And here's a radical notion: you can actually change your code if you wish. You know, add features and functions. You're allowed to do that. :-) You run code as long as it has value on the mainframe, for as long as you wish, without the vendor saying, "Sorry, that code must die this year." Just keep your OS and middleware on at least relatively recent releases, that's all -- it's backward compatible. Change your code and add code as you want, when you want.
I think the generally-accepted criteria for a mainfame are:
(1) multi-user with fine-grained security model
(2) multiple access mechanisms (LAN, WAN, multiplexed terminals)
(3) multiple storage layers (caches, core, paging devices, disk storage, backup media), with redundancy and partitioning
(4) high-scalability, high-throughput busses
(5) error detection and correction (ability to 'rewind' your virtual machine at least a few steps back) which typically requires CPU redundancy, very good management of CPU state, and SECDED memory
(6) multiprogramming with good handling of parallelized tasks
(7) batch execution, and automatic recovery from nearly every imaginable error condition
All of this needs to be pretty transparent to applications and users, too.
--TheOrangeSquid Is it any wonder things seem so awry? We swim in a sea of confusion and don't have to think to survive
RAIS is great idea call me when they have invisible failover. The only company I know of doing this with PC hardware is Stratus. I'm talking about not losing any processing due to a machine or OS borking. I'm serious if you have this then the problem is solved.
Last time I looked the Linux/HA and all other projects had some serious issues with failover, there always seemed to be a single machine at some stage that could take the cluster away from the user.
The AS/400 like the mainframes has been built to be reliable. Hardware costs because it's specced not to fail, redundancy on everything is available. Not to sure about a processor failure on the As/400 though, might still be able to take the machine down. But everything else failsover cleanly.
So what have you?