Lamont Granquist <[email protected]> writes: > > I've seen a lot of IT managers jump on the virtualizaiton bandwagon, but > > then > > when forced to defend their numbers have been unable to do so. > > yep. > > that's basically my problem. > > i'm also not seeing the justification for the associated infrastructure > for example, why have 4 GigE drops per server, when we have 400 servers in > a business unit that do around 600-800 Mbps peak across every interface > and every server? why have a lot of shared storage when we basically do > no i/o (as well as no CPU and no network).
Yeah. virtualization is a tool for making larger servers look like a number of smaller servers. it only makes sense if you need servers that are smaller than the optimal server size. (by optimal server size I mean, if you buy a dual-core server with 2gib ram and co-locate it, you are paying a lot more per unit of cpu/ram than if you buy an 8 core 32GiB ram server. But then, if you buy a 32 core, 128GiB ram system, you probably go back to paying more per cpu/ram unit. There's a certain size of server that it is the cheapest to buy/host. Virtualization makes sense if that server is larger and more powerful than the servers you want to use.) Usually the super giant servers make no more sense than filling up my rack with atoms. (atom boards actually have a horrible performance per watt, when you consider that they eat about 50w each, are limited to 2GiB non-ecc ram, and have absolutely pathetic CPU performance. If you could get an atom with a chipset that only ate 5 or 10 watts, like you can on a netbook, they'd make a lot of sense in a lot of places. But with the 945GC chipset, they are garbage.) > > one thing that a lot of people initially see is 'hey, we are reducing the > > number of servers that we run, so we will also save a huge amount of > > sysadmin > > time', what they don't recognize is that you have the same number of > > systems > > to patch (plus the new host systems that you didn't have before), so unless > > you implement management software at the same time your time requriements > > go > > up, not down. > > yeah, well since i've got a strong configuration management background > that is one thing that is obviously wrong. Many people outside the field think that most SysAdmin time is spent monkeying with hardware. But there is some truth to the 'virtualization can save you sysadmin time' marketing bulletpoint, assuming you have a big 'maybe' or 'sometimes' in there. If you really do need a whole lot of trivially sized services, virtualization and giving each small service it's own 'server' can sometimes be less work than making your mailserver config play nice with the apache config and the fileserver config and the db config on the one giant monster server. In that case, virtualization can also make it easier to make the db server the problem of bob in accounting without letting him have root on your webserver, and let the fileserver be the problem of jane in IT without letting her have root on the developers' git server. Granted, you can do the same thing by just running different services under different users, but that's easier with some applications than with others. > i spent quite a bit of time beating up some citrix reps drilling down into > what they can do for box builds and configuration management, and > virtualization's approach was basically to increase the velocity of being > able to do the disk duping approach to deployment and configuration > management which does nothing for life-cycle configuration management > (e.g. changing /etc/resolv.conf on every existing deployed server). i've > seen virtualization pitched in CTO/CEO-focused materials as "solving" > configuration management, however. How come anyone still listens to sales? I mean, the last person I am going to take advice from is someone who has an obvious interest in deceiving me. But yes, I find this "everything is an image' approach that the virtualization folks seem to be taking to be very wrong. I think the only rational way to manage virtual machines is to manage then the same way you manage your physical machines. Cobbler/Coan is actually pretty good for this sort of thing. For prgmr.com, I'm actually working on a paravirtualized netboot environment, so that customers can manage physical and virtual servers (hopefully even physical servers that aren't hosted with me) using the same tools. Anything else, I think, is insanity-- It's just plain stupid to keep adding more tiny virtuals to your cluster once you need the power of multiple physical boxes. -- Luke S. Crawford http://prgmr.com/xen/ - Hosting for the technically adept http://nostarch.com/xen.htm - We don't assume you are stupid. _______________________________________________ Tech mailing list [email protected] http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
