[TAG] "I'll do it myself, thanks" open-source app: Gobby (cf. SubEthaEdit)
rick at linuxmafia.com
Wed Nov 2 09:00:04 MSK 2005
Quoting Benjamin A. Okopnik (ben at linuxgazette.net):
> [blink] Pardon my absolute ignorance of the above. What is this "virtual
> hosting" and whatsit frameworks among your people? It seems that I know
> zero about the things that, from your suggestion, I most need to know
All of those are things sort of vaguely like VMware, except open-source.
Ordinarily, one of the reasons hosting a machine at a colo (Internet
co-location centre) is expensive is that your bitty box occupies rack
space, and also gulps down AC power (mains power, for
Commonwealth-English folk). This is one of the reasons the 1U form
factor (and even more unwise things) has become so popular for server
farms: It allows you to fit 40 1U servers into the same 19" rack that
otherwise would have been limited to about 20 standard 2U servers. (As
standard rackmount servers have become shorter, the engineering required
to prevent self-immolation from heat buildup has become much more
Xen, UML (User-Mode Linux), and QEMU are all virtual-machine
technologies ("virtualisers"), implemented entirely with open-source
code, that allow you to run multiple virtual machines underneath Linux.
Each virtual machine can run the Linux distribution of your choice,
which while running believes itself to be running on native hardware as
the sole operating system, unaware that the "hardware" it's running on
is emulated by a virtualiser that intervenes between it and the
Xen is the most-recent of those virtualisers on Linux, and is looking to
be wildly successful as a hosting environment for colos that run Linux.
You sign up to get root on a virtual "machine", which gets preloaded
for you with the distro of your choice. After being given the initial
root password, you ssh in and do... anything you want, including opening
a chroot and installing something else entirely. After all, you're root
-- a veritable microcosmic god.
Limitations? I suppose the colo might impose I/O throughput limits
on each emulated ethernet interface -- or not, per contract. Also, the
underlying physical hardware only has so much excess capacity: If all
20 or so emulated hosts on a physical 2U box start doing database
rebuilds all at once, odds are that performance will suffer. On the
bright side, that probably won't happen often, and the existence of
those 19 others means you'll probably pay only 1/10 of what having the
box to yourself would cost.
(I'm assuming those are real, modern Linux machines, something like a
dual 3GHz Xeon EM64T or Opteron, not an antique piece of junk like
uncle-enzo.linuxmafia.com's single-proc PIII/500 and Intel N440BX
> > You can also own your own domain, and virthost just the mail for it
> > somewhere, if nothing else: [...]
> "virthost the mail"? I suspect the answer is connected to the above.
No, what I meant by _that_ is something even cheaper.
Let's say you registered okopnic.com as your personal domain. You get
a couple of friends to agree to do DNS for you (which is simple, and no
big deal). Now, you're all dressed up but have nowhere to go, because
your $15/year for the domain plus two friends' nameservice has got you a
functional domain (i.e., it resolves names), but no host to _live_
within that domain.
So, you talk to me, and say "Rick, could I receive my mail for FQDNs
okopnic.com and mail.okopnic.com on your linuxmafia.com machine?" And
I'd say "Sure." And I'd have no real need to charge you a penny for
Old uncle-enzo currently answers to just a few FQDNs (linuxmafia.com,
uncle-enzo.linuxmafia.com, www.linuxmafia.com, ftp.linuxmafia.com,
enzo.linuxmafia.com, ns1.linuxmafia.com, mail.linuxmafia.com,
debian.linuxmafia.com, and mail.linuxgazette.net), and _used_ to also
answer to hugin.imat.com -- but can respond to a hundred domains pretty
much as easily as it can to one.
You'd tell your friends who maintain your DNS zonefile to point
okopnic.com and mail.okopnic.com to uncle-enzo's IP, 188.8.131.52,
and you'd be in business. Well, you'd be in business after a few days
of my debugging MTA-configuration errors, but that goes with the
> [grin] Thanks, Rick. Perhaps I don't mention it often, but I do
> appreciate it;
You're very welcome.
[entry in /etc/sudoers to let you install packages:]
> Thank you! That would be really appreciated. Can't think of any to
> install at the moment, and will vet anything potentially questionable,
> of course.
And it's done!
 Actually, it badly needs to be migrated over to the pair of used 18GB
10kRPM SCSI drives my wife got me for $5 each at the BarCamp auction,
instead of the laughable pair of very old 9GB that have operated it for
a dog's age -- but in principle it _could_ service mail for a hundred
domains pretty easily.
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