Lamont Granquist <[email protected]> writes: > On Tue, 15 Sep 2009, Daniel Pittman wrote: > > For what it is worth, I have found that "container" solutions often scale > > better to the actual workload than "pretend hardware" virtualization does, > > because it shares RAM between the containers much more easily for these > > tiny, > > almost nothing, applications. > > Well, BackInMyDay(tm), we use to just run multiple apps on different ports > and let this novel thing called a "process scheduler" let the server do > two different tasks at once.
Yup. much lower overhead than virtualizing stuff, in terms of CPU cycles and ram. Oftentimes, more sysadmin work, though. > i'm still a bit unconvinced that virtualization really solves any > fundamental problems over just managing multiple running software > instances on the same server. The thing is, if I have 8 2GiB p4 servers running various flavors of linux, doing different tasks, I can consolidate them all on to one of my new 8 core 32GiB ram boxes, and save a lot on power. If I do that without virtualization, I will save some cpu power/ram, but it will be more work. I've gotta move everything to running on the same linux version, and I've gotta make sure the sendmail config for the apache server doesn't step on the sendmail config for the mail server, etc... doing it with virtualization is usually less sysadmin time, but it wastes some cpu/ram. A previous poster suggested os-level virtualization like OpenVZ; that is sort of a middle of the road solution between consolidating the old fashioned way and fully virtualizing. It's more efficient that using paravirtualization or full virtualization in terms of cpu/ram, but it's also more work. all servers need to use the same kernel, and if one machine eats a lot more resources than it should, you really need sysadmin intervention. (personally, I prefer paravirtualization for this reason. I host untrusted users, and I don't mind throwing away some ram if it means I don't have to worry about it when some joker decides to run mprime, or when someone tries to run a giant webapp on the smallest plan.) You can further tweak OpenVZ so that it errors on the side of automatically killing heavy processes rather than letting them effect the rest of the system, but for partitioning, it just can't touch a paravirtualized system. I've had several consulting gigs where I show up and the client is expecting a big performance gain out of using virtualization over consolidating the old fashioned way. The gig usually ends pretty fast when I explain that just isn't how it works. -- 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/
