Slashdot Mirror

← Back to Stories (view on slashdot.org)

The Practical Value Of Mainframe Linux

Posted by ryuzaki0 on from the one-for-each-cousin dept.

Sun Tzu writes: "Just in case you're wondering what else to do with the mainframe in your basement, here's some useful information to help you prepare a proposal to management." The article is clear and candid, noting things like, "In some discussions the issue of the S/390's 'five 9's' reliability is brought up. However, IBM's 99.999% uptime claim is for clusters of mainframes, not a single system." And no, running 40,000+ virtual Linux boxes is not that practical. Still and all, I wonder how much an S/390 will cost in 3 years ...

2 of 75 comments (clear)

  1. S/390 Dinosaur? S/390 Expensive??? Shyeah right! by Chanc_Gorkon · · Score: 5

    Some people, invcluding the author of this article have NO clue about true costs involved in a S/390 system. The system itself can cost as much as a mid to high end Sparc box. The processor is at least as powerful, but that's not why you'd want to use it as a web server. Mainframe has KICK BUTT I/O. Mainframe are MUCH more efficient at pumping I/O. You could use a mainframe to stream audio or video on your web site with copy, and a another copy could do the web serving. Also, the main cost of operating a mainframe is NOT just the hardware support, it's the software. We pay one vendor 20,000 a year just to get support and software updates! With Linux under VM, only thing you have to pay for is VM. You can load as many copies of Linux as u want on the mainframe. Also, you could probably use existing bus and tag and ESCON devices such as printers, tape silos and DASD as native devices under Linux. There are mainframe printers that can print 90 plus pages per minute! Granted, some of the mainframe reliability can be attested to software, but on our current system, we have 2 power feeds (you split those between two power substations), we have had RAID for YEARS longer then PC server's have had and we have been serving 2-3 million data requests a day and this was on a 10 year old mainframe, running DOS/VSE, a cousin of the first mainframe OS that MVS was to replace, but is still going strong. Our new one hasn't even scratched the surface of the power we have available. Oh and lest I forget, they can call themselves for service before they die. We have had disk packs go bad and we NEVER went down or knew we had a pack go out. Also, ESCON, a fiber based way to connect channel devices to the mainframe, can have a range of 4-5 MILES before needing a repeater (if one wants to lay that much fiber! Be cheaper to use the OSA ATM or Fast Ethernet adapter and do it with TCP/IP).Um, lessee, scheduled downtime is limited to changing time (we have to do it this way to preserve data integrity), some software updates do need a IPL too, OH and in my opinion, the MF can boot faster too! Gork

    --

    Gorkman

  2. How Linux/390 might really be useful by Pinlighter · · Score: 5
    From the perspective of a mainframe system programmer, I have to say that the 40,000 linux VM machines never really seemed that useful. 40,000 systems is 40,000 things to maintain and configure, never mind whether they are on separate PCs or in virtual machines

    What that original article was really going gaga over was VM. I can understand that - VM is really sweet - but I doubt the configuration would be that useful.

    However, I think Linux could be useful to mainframe sites like us. Here's why:

    • IBM run something called Unix System Services under OS/390. This allows you to have a Unix filesystem on OS/390, TCPIP, and all the open sysem stuff.
    • IBM have ported Apache (=Websphere), Lotus domino, and a bunch of other stuff to this environment
    • And we are using them
    • This is nice for us, but now the drain on our system is forcing us to partition it (well, we anticipated that)
    • So we are going to have a partitioned system with one slice basically running OS/390 to support Unix System Services, Websphere and Domino.

    Very straightforward - except that the overhead of running OS/390 just to support Unix System Services is high.

    Therefore I'd say that a probable - no, make that possible - future configuration for us is a partitioned S390 box with one slice running OS/390 and hosting the database and the other running Linux/390 and doing the web serving. Much lower overhead, I'd guess.

    (why not do the web serving from a RS/6000? Because our databases and so on are on the OS/390 system and the S390 will allow very fast datasharing, much faster than anything across a network).

    I'd love to install it and try it out

    BUT there is no way places like ours will make a commitment to Linux/390 without substantial IBM support.