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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
All that still exists for VMS, and it runs on Itanium. There is some serious work being done on getting it to run on Opertion as well.
What they have failed to do is avertize properly so people know what it can do and what it cannot.
Never answer an anonymous letter. - Yogi Berra
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.
It's true the AS/400 is an expensive platform. It's also true you save money every year because you don't need sysadmin's or DBA's (at all at the low to medium end and much less at the upper end). Additionally, in my experience with similar workloads between AS/400 and PC servers, you need lots of PC servers to match the throughput in OLTP applications.
I think when you balance these things, the AS/400 is much less expensive than it may seem when you are buying disk or memory at extremely high prices.
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?
The main reason companies have decided to move off mainframes has more to do with extravagant licensing fees than anything else. Well-written mainframe software (even old Fortran or COBOL stuff) is no harder to maintain than newer stuff, and it's often much less susceptable to things like memory overflows and the like.
That's one problem with hearsay -- it can sometimes be accurate, but sometimes wildly offbase. :-)
Almost all of our mainframe stuff is Fortran with some MASM and other languages thrown in, but we're not using IBM mainframe, either (our older stuff is all running on Unisys big iron).
I've played on mainframes professionally now for 18 years (19 years in August!), and I love the history of the platform as well as the relatively bulletproof application environment I get to work in. If only we had some of the same tools on Solaris!
Mainframe/UNIX Bit Twiddler and long time Windows/Linux Hobbyist.
The Theorem Theorem: If If, Then Then.
Well, it nearly was. Back in the old days, IBM thought that its /360 architecture was getting outdated, and came up with an advanced OS, with potentential for 48-bit addressing (pretty radical in 1978) and integrated relational database. It was, of course, completely incompatible with everything else they had, (remember when IBM stood for 'Incompatible Bits of Machinery?)
/360 line was quietly buried, and a machine using the architecture - the System/38 http://en.wikipedia.org/wiki/System/38 - was lauched, to the general confusion and indifference of the marketplace.
/38 was the basis for the AS/400...
They then realised that their customers had shitloads invested in CICS/COBOL apps, and the competencies to maintain them, and were not about to spend millions rewriting them...
Hence the idea of 'replacing' the
I was one of the original S/38 fanboys when it came out - a superb machine and OS that was far more powerful and easy to use than the 360. The
So could say that the AS/400 was the 'mainframe than never was'