To continue a conversation I started with Jake on Tuesday night....
Some reasons why I like virtual private servers compared with the two
alternative options - "shared" hosting and dedicated servers:
* Unlike shared hosting I have full SSH access to the server, and can run
my own choice of O/S, and can install non-standard services if I wish
(eg I tend to use xinetd or variations on it to provide specific
handling of incoming connection, which I couldn't do on shared hosting).
* Like shared hosting, the cost of maintaining the hardware is shared
between multiple customers, and is therefore cheaper. (Of-course the
resources are also shared, and unlike "shared hosting" a lot of the
processor and memory overhead goes just in handling the O/S, but it's
quite possible to get decent performance on a shared host all the same.)
* Unlike dedicated servers, "hardware" upgrades can be quite quick, since
they are only virtual hardware. So increasing disk or memory capacity
usually means a quick config change by the host, then a reboot of the
virtual server, and you're up and running with the new hardware.
Compared with physically swapping a hard disk or installing new memory
this is much faster.
* Unlike dedicated servers, the hardware can be virtualised, and therefore
it is trivial to move a virtual machine between servers of different
hardware specifications without affecting the virtual machine. This
would presumably depend on the virtualisation technology though? (I've
not played with Xen but I believe it is closer to the real hardware and
therefore less easy to move between different hosts?)
* Related to the above: you only need the chosen host O/S to have drivers
for the physical hardware; the guest O/S's only need drivers for the
virtual hardware which is a known quantity and rarely changes. Therefore
supporting a wide range of O/S's is much simpler.
* The provisioning of a new virtual machine is just a software job, so no
physical hardware needs building up and configuring. It's therefore an
ideal platform for experimenting, and hosting a virtual machine for only
a month or two need not be cost prohibitive.
Of-course I don't manage a hosting company, so I don't get to see the hassles
from the host's end. The main disadvantages are that you're losing a lot of
processing capacity to managing the infrastructure, but that's fine for me as
I don't need anything like the capability of a modest current-spec server, and
without virtualisation I can't realistically have just half of a server (or,
in my case, probably only 5-10% of a server).
However, I'm interested to hear the counter arguments. I currently use virtual
servers starting at around £10/mo for 512MB RAM and 20GB disk space. Assuming
a 30:1 virtual to host server ratio (I have no idea what the real figure would
be, I just took 16GB / 512MB RAM = 32 machines) that's an income of around
£300/mo for that server. Is that sufficient to provide a decent service at a
decent margin? I have no idea!
--
Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450
Registered in England (0456 0902) @ 13 Clarke Rd, Milton Keynes, MK1 1LG
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