[gentoo-user] Re: Managing multiple Gentoo systems

[Nicolas Sebrecht <nsebrecht@piing.fr>]

The 06/07/11, Grant wrote:
> >> After a frustrating experience with a Linksys WRT54GL, I've decided to
> >> stick with Gentoo routers.  This increases the number of Gentoo
> >> systems I'm responsible for and they're nearing double-digits.  What
> >> can be done to make the management of multiple Gentoo systems easier?
> >> I think identical hardware in each system would help a lot but I'm not
> >> sure that's practical.  I need to put together a bunch of new
> >> workstations and I'm thinking some sort of server/client arrangement
> >> with the only Gentoo install being on the server could be appropriate.
> >
> > I maintain multiple Gentoo we mostly use as KVM hosts systems (and
> > coming embedded routers). As KVM hosts, some of them are very sensible.
> > Due to the contracts to our customers, I have to do with various update
> > strategies on top of various hardware.
> 
> Thanks to everyone for some very juicy tidbits.  I'm rearranging my
> thinking on all of this.  I think the key for me may be to combine
> systems with separate functions in the same physical location into a
> single system.  Does the KVM thing work well?

KVM itself works very well here, even with advanced features such as KSM
pages sharing.

The difficulties come with Microsoft products for both good integration
and perfomance (I would recommend RAW format, iSCSI or plain physical
partition instead of qcow2, for example). That beeing said, I finally
have all working well for XP, NT2003 and 2008 servers.

I use libvirt on top of KVM which is in the way to become very good AFA
you don't rely on libvirt's API which tend to move a lot.

>                                                Running a bunch of
> workstations as nothing more than wireless KVM setups on the same
> system?  I should be able to cut my Gentoo systems down to just a few.
>  Basically one at each physical location.

I would be much sceptical for both workstations and wireless guests than
for servers:

1) For workstations, things are currently changing with the very recent
and "not much usable with Gentoo, yet" spice software. I expect a lot of
improvments in the coming months for this use case. I would say it's not
ready for production, yet.

2) About wireless virtualization it's highly depending on what you aim
to do, especially if you intend to use the PCI passthrough feature to
give your wireless card to a guest. For this to work, you MUST have your
hardware (CPU, motherboard and PCI card) VT-d compatible which is
currently NOT a piece of cake, today. It relies on industry and
manufacturers moving not as fast as software. I would expect more widely
VT-d cards in the coming _years_.

Now, if you intend to use the wireless card from you hosts and share
networks using bridge utilities it _MAY_ be OK: Linux bridging does not
always work with all wireless cards (see http://tinyurl.com/ylcutwv for
more information).


In a more general approach, when I hear "routers" and "wireless" I'm
more thinking _embedded_. KVM/qemu would only help you to build your
target systems.


For embedded (or tiny, at least) systems, I would not use LXC.

The drawback with Gentoo is that the current official uclibc stage3 for
embedded/tiny systems is obsolete and marked as experimental. In facts,
it's very _hard_ if not impossible to use it these days. Making your own
cross-compilation environment is not a piece of cake (too), even with
dedicated tools such as crossdev. This topic would ask its own book.
So, if you want to try Gentoo embedded save your time by working on
unofficial stage3.

-- 
Nicolas Sebrecht