Managing Linux and Virtual Machines?

deijmaster asks: "For a couple of months we have been hearing (as a major consulting firm) IBM people pushing the possibility of installing a Z/Linux VM setup at one of our biggest clients (financial). To a Linux user such as myself this sounds great, at first. Now, I am a bit reluctant when it comes to managing this kind of infrastructure, with little or no local expertise at IBM. Has anyone gone through a Z/Linux VM corporate installation and lived through the management of such a solution?"

Comments

Re:No.

[sglines]

I once saw Amdhals version of Unix running on a mainframe at New England Telephone. The ps command yielded about 20,000 running processes and the guy I knew told me that it was just one of 6 VM systems running on the same hardware.

I was impressed.

SG

No fear...

[(H)elix1]

Just consider it VMWare for big boys. I'm doing a wee bit of development for Linux on zOS, and most things just work once you get it installed. Lots of options, depending on how you carve up the system. Anyhow, for the most part it is all about fast i/o, rather than monster processing power.

Picked up Linux on the Mainframe over the weekend, but plan to read it on a (very long) plane ride next week - looked like it focused on care and feeding, however.

Dunno about Z/Linux but...

[rimu guy]

I haven't worked with a Z/Linux VM before. However, I have used User Mode Linux to create a dozen or so virtual servers per host server. And I'd imagine that the benefits offered by UML would also apply to Z/Linux VMs.

For example, with UML you're able to get much better resource utilisation. e.g. most of the time the machine is idle. When one of the UML servers need the host server's resources, they're there (CPU, network, disk IO, etc). That means you can have multiple UML servers bursting up to the performance potential of the host server. Certainly a better resource utilisation than having several host servers running mostly idle.

Another benefit of virtual machines are their logical separation from the host server. Each virtual server has their own users (including root), applications, file systems, IP address, etc. That means that if security is compromised on one, the others are unaffected. Ditto resources can be allocated to each virtual server according to need. And any mis-configuration on one doesn't affect the other. This compares to running multiple applications on the same server for different purposes (e.g. running HR and Account systems on one server, if email goes down them both systems are affected. In a virtual server setup, only one of the other would be affected.

So... Thumbs up to server virtualization software in general. Particular kudos to UML. And good luck finding out about Z/Linux!

- P
RimuHosting.com - Linux VPS Hosting

It works well

[dalslad]

I sold and installed the very first Linux application on the S/390 --a Multiprise running VM and it worked great. We used the TurboLinux port and then finally wound up with SuSE.

We compiled the source code and it ran just like it did on a big Intel box. IBM helped with hardware issues which related to load balancing amongst the VM instances. One of their business partners supported the customer, Winnebago Industries with regard to Linux and OS 390.

IBM wasn't much of a factor as far as needing support. They supported the mainframe, the OS and VM just fine. SuSE installed without a single issue.

Some other issues arose in getting the user to learn IBM mainframe lingo, such as IPL instead of boot, and DASD. But, that didn't require much effort. The IBM Redbook on running Linux on the S/390 was all we needed to transfer knowledge. We downloaded it for free in pdf format.

The main benefit I discovered was the ability to consolidate servers. We replaced a bunch of M$ Exchange servers and ran a suite of Open Source apps such as Cyrus IMAP, Open LDAP, Exim, Apache, etc. We were able to get rid of a bunch of distributed servers and put them on one instance.

I suggest that IBM can help, but I don't think you'll be dependent on them. They're very expensive. With Linux on the zSeries or S/390 you can do everything yourself. -- That might not be what IBM wanted, but then they championed Linux, didn't they!

Re:It works well

[swillden]

With Linux on the zSeries or S/390 you can do everything yourself. -- That might not be what IBM wanted, but then they championed Linux, didn't they!

Oh, I think IBM will be just fine with that. Sure, they want to sell services, but selling mainframes is also a lucrative business -- more lucrative than services, in terms of gross margin. Whether you need their services or not, they're getting paid. Even if you already have the mainframe and don't need to buy one for the project, eventually you'll fill it up and need more power. They'll wait.

IBM understands the value of long-term client relationships; they'll ultimately get a lot more of your money if they don't try to take it all now. What's really interesting about IBM is that they've now learned that they'll ultimately get a lot more of your money if they make it easy for you to buy elsewhere.

See, if customers feel trapped, they'll often willingly suffer short term pain so that they can avoid being caged forever. IBM has realized that if they give the customer open solutions, (a) they gain a short term competitive advantage over closed solutions and (b) they make customers comfortable, happy and trusting. Then, as long as all of IBM's offerings are reasonably competitive, the simplicity and convenience of having a single IT vendor will allow them to paint the customer's entire infrastructure Blue, while the customer sits serene in the knowledge that if needed they can always go elsewhere. IBM, of course, will try to ensure that the customer never feels that need.

IBM's ultimate goal in every client relationship is simple: They want to get to the point where whenever anything is needed, the CIO's first move is to call his IBM client rep. Or, even better, for the client rep to pick up on the CIO's frustrations and point out the need, and IBM's solution, during their twice-weekly lunches, or when they're golfing, or having a barbecue at one or the other's home. To achieve that, it's not necessary that buying IBM always be the best idea, only that it's the easiest idea and that it's *never* an egregiously bad idea.

This works, and it's a strategy that's completely out of reach of every IBM competitor because none of them have the size to pull it off. Well, HP might have the size, but lacks the breadth and the customer focus, at least so far.

So, in your case, IBM is just fine with it, because even if you didn't buy the services this time, you're an "IBM Shop", and you're happy. Some day when a new project comes up and your staff is just tapped out, or when a new technology comes along and you don't have time to understand or deal with it, the happy Blue glow that emanates from the smoothly-running z-Series will convince you to call IBM and "just let them handle it". And handle it they will, with a 30-40% profit margin.

Avoid misunderstandings...

[LinuxHam]

I'm an IBM'er currently on assignment at the world's largest insurance company. I was brought in because they wanted to consolidate servers to a mostly-Linux solution. After piloting Samba 2 beta on zLinux last summer, they balked at the heavy reliance on Z.

The key is for people to realize that the type of workload is critical when deciding to try zLinux, and any barking about Athlon vs. G6 is useless. Also, vendors need to realize that once you compile an app on Linux on any one platform, you're usually a recompile away from running it under Linux on any other platform. Hence my reasoning that any complaints about software availability from a year ago is also useless. More apps are being ported to zLinux everyday.

Linux on Z has a role, it just needs to be explored by more brave souls. Besides, I've always said that if I leave the company, I'd like to create an "ISP in a box" using a z800 and some ESS disk to host a few thousand virtual web servers. I implore people to please visit Linux@IBM for more information.

lead balloon filled with hot air

[smoon]

We've got a production linux instance running under VM alongside our production VSE system. Since the box is fairly underpowered we get a minimal slice of the CPU. This makes the system respond like a 286 with the 'turbo' button turned off.

When the VSE instance bombs out for some reason, and we get effectively 100% of the CPU it responds like a pentium... maybe. Think P166.

Unfortunately in our circumstance we can't 'turn on' more MIPS because then our VSE instance is running on a 'bigger' machine and we end up doubling our licesing costs. Other alternative is to turn on the ILF (integrated linux facility) which dedicates 120Mips to linux only, without affecting other licesning, but that costs $150k. You can buy a lot of 2-way or 4-way pentium boxes with decent RAID arrays and get much better performance for that kind of money.

So if your shop is run by some sort of morons and you've got 100's of spare MIPS to burn, then Linux on the mainframe probably makes some sense. Otherwise, just get some intel boxes. Any savings the mainframe provides in terms of power, cooling, and ligher administration is going to be offset by massive complexity, poor performance, and a lack of easy support for a bizarre platform that few developers have access to.

Re:A little one-sided. Here's the downside of VMs

[afidel]

IBM mainframe complexes basically never go down. There are installations that have been running 24x7x365 for decades. That's the whole point of owning one.

Sticker Shock

[delcielo]

We're fortunate to have a good solid VM guy, so implementation was no big deal on our dev box. But we've noticed a few things along the way...

VM is expensive. Engines on the mainframe are expensive, and are the weak point in Z/Linux. Mainframes normally run batch types of workloads, and have great big fat I/O. They're not necessarily great processing powerhouses.

You can download Linux and install it on the mainframe; but you get zero support. If you want support, open up that big old budget again. When we looked at it, Suse wanted about $20k per year, and RedHat wanted $24k. We flew solo instead. So far it's been fine; but be prepared to pay if you want support (which, by the way, is something the PHB's and mainframe systems programmers are used to having.)

As for operational considerations, I haven't really had any problems with it at all. There aren't many rpms out there for z/os; but you can compile almost anything and use it.

Installation is kind of cheesy; but not horrible. You basically set up your vm guest, log in to it and ftp the linux kernel, ramdisk and parmfile to the guest dasd, giving it a fixed record length of 80 bytes. You then feed these into a virtual card punch (that's right, a virtual Hollerith Punch Card Reader - 80 columns = 80 bytes), then into a virtual card reader, and ipl the reader.

This gives you a running instance of linux that you can use to do a net install of the full distribution.

In the implementation class I took, I was partnered with a mainframe guy who was complaining about how archaic vi was. It made me laugh.

"Dude. We just chopped my kernel into 80 byte blocks and fed it into a card reader. Don't talk to me about archaic."

Re:Z/Linux at a big financial firm

[Alizarin Erythrosin]

"IBM has been great in getting us set up, but they don't live with the systems."

This is a very, very, very important point to consider. If you let IBM run the whole shootin match from a distance, and something goes wrong, expect downtime.

This isn't related to Z/Linux but it is related to IBM and their systems management. At the business of my employment we outsourced all our network/systems administration to IBM. In the past 2 months (July and August) we have had not 1, not 2, but 4 very very major worm/virus infections that shut the entire network (as well as business) down. IBM didn't keep any systems up to date on patches (and the corporate security department didn't help either... they approved Win2k SP4 in an awful hurry after they found out it contained the Blaster worm fix) and told us to leave our unprotected computers on 24/7 and they would update them "in the next few days." I leave the determination of what happened after that as an excercise to the reader.

But hopefully IBM won't do that to your Z/Linux VM... Hopefully you'll have someone on site who knows their stuff, even if it has to be you (hey, then you can ask for a raise!)

This is being done right now with VMWare also

[nomad_monster]

One of my clients, a large insurance firm in the New England area, is in the process of consolidating their NT environment onto VMWare ESX server, which is linux based. This is an IBM X440, running about 30 consolidated NT VMs. Since it's VMWare it can also run linux VMs. They are saving about 500k annually on this setup in associated costs for hardware/support/environmentals. This was a pilot, and they are going to be moving forward with more consolidation based on this.

This really isnt a new concept, most of us know of the IBM P-series, Sun E-10ks and 15ks, and the HP Superdome. All use virtualization in one form or another to provide this kind of setup. Z/series is kind of novel, because....hey...its a Mainframe.

Re:Mainframes

[lrichardson]

Not so much anymore.

They're a heck of lot less wasteful (electrickery into heat) than they used to be, and require a lot less space (again, compared to the past).

Clusters ... I don't know where you get the 'faster and cheaper' line, unless you're talking about applications specifically designed for clusters. When you start writing apps designed for a few thousand simultaneous users, the benefits of the mainframe become apparent. Stability. Speed. The ability to hold gobs of info in ram. Which, BTW, makes them the nearly ideal web server. Security (hey, it's not M$!). Mainframes are a mature technology ... meaning lots of the annoying things (both hardware and software) still plaguing the small boxes have been fixed. (Admittedly, 'mature' often translates into 'f$cking obsolete pos' (i.e. panvalet).)

I don't worry about backups conflicting with apps on the mainframe. I don't worry about the details of storing things reduntantly (although that's quickly getting solved on the smaller boxes). For those things written on WinWhatever, the programmers need to worry about every little upgrade/patch from M$.

Now, most places still give mainframes a room of their own ... and it tends to be a bigger room than servers get. And, if you're happy with something a little slower and little less reliable, a good farm runs less than a mainframe.

But, to put things in perspective, one of my databases (non-mainframe) is moving to a USD 2.1 million machine. That's a fraction ... as in, from 1/4 to 1/20 (depending on options) of a mainframe.

I'm working in both worlds. I like the cost benefits of the smaller boxes. But it still freaks me out when users punch in a query and it takes several seconds (to minutes) for a response, when the delay on the mainframe is done by the time the enter key pops up.

Its worse elsewhere...

[buddha42]

If you think the dissenting opinions on this thread are bad, read the Linux390 mailing list. One thing just about everyone agrees with on the list is this. Do not buy a mainframe to run Linux. If you already have a mainframe that has some spare cpu time, look into consolidating simple services onto LiuxVMs. Generally speaking linux on the mainframe relies on "well in this case" situations that make it cheaper. For instance you can use Samba on a LinuxVM to have a very reliable file-server, but DASD and Shark's are bloody effing expensive compared to pretty much any other system. However, if you already have a well enginered backup system and all the neccisary licensing, perhaps that tips the costs back in favor (or at least break even). There are a great many who see Linux390 as half "geeks looking to do something nifty with linux" and half "IBM looking to show off its linux-commitment and get some free press about its mainframes". Because when you really learn about all the options, benefits, and limitations, there are suprisingly few situations where it's worth it.