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Re: recommendations for a Xen/NetBSD box?
Luke S Crawford wrote:
Carl Brewer <carl%bl.echidna.id.au@localhost> writes:
So if you were going to build a Xen server to host a NetBSD 4.0 (i386)
production (ie: must be stable!) DomU and a couple of others as
development/play domU's, what would you suggest as the Dom0 and what
version of Xen should I be looking at?
Your trouble is NetBSD/i386 -stable only runs in non-PAE mode (if you
are cool with -current, there is PAE support for DomU) and the
PAE mode of the Dom0 and the DomU must match.
Dumb question, PAE means exactly? Is there an FAQ I need to go through
before I ask any more? :)
CentOS (and I think most distros) assume your xen kernels are PAE.
so if i386 is essential, you will need to re-compile all your Linux
kernels to disable PAE (it works fine, and it's stable; it's just
kindof a pain, because you don't get binary updates)
Your problem is solved if you are cool with runing on x86_64 (your
chip will support it) if you make a 64-bit Dom0, if you use xen 3.1,
32-on-64 should work for linux/PAE-i386 DomUs, but 32-on-64 is really
32PAE-on-64, so it still won't get you i386 NetBSD DomUs)
But yeah, if you want i386, you are either running NetBSD-current or
you are running the whole box non-pae. Running the whole thing in
x86_64 is really quite a lot easier.
Thanks Luke, maybe I need to give a bit more background. I have a
current NetBSD 3.1 server, running sendmail, cyrus, a couple of
zope/plone instances and some general purpose stuff on it, and it's also
a build server for some of my client sites - I look after a few NetBSD
smb servers & Internet gateway boxes etc, they're either 4.0 or 3.1 (one
is still 1.6 ... but it's slated for an upgrade as soon as I can
convince the client it's necessary). So binary compatibility is a
feature I want to keep on it with the other NetBSD boxes I manage, and
also when I migrate the current server to it (Cyrus and Zope in
particular I want to be able to pick up and drop off and have 'just
work' on the new xen-ified server. I understand that if I take the
server to 4.0 I'll need to bump the other sites up, but I can manage
that, but -current is not an option. Proper releases only. There's a
xen kernel that comes with 4.0 and 3.1, it's Xen 3 I think?
I also have a CentOS (RHEL) 5 box, that is a development box I use to
test & devel on before installing into a co-located server interstate in
a data center, running the same (CentOS 5). This needs to be as
bog-standard as possible as I don't have console access to the remote
box so it needs to be standard and stable, which is why it's a RHEL
ripoff, not one of the other more volatile distros.
I want to replace one server with two, to cut down on power bills etc
and also make my disk management a bit neater. One set of RAID 1 (or
ZFS mirror) disks is a lot neater than having to manage three different
O/S's sets of disk management tools.
I'm also dabbling with Opensolaris (I want ZFS!), so if that can be
played with in a xen environment all the better. My office at the
moment is overflowing with PC cases and my KVM switch is bursting! I
know I can do this with vmware, but Xen appeals to me as it seems a lot
more efficient than vmware and it's idealogically better.
(oh, and a note, the hypervisor is the xen.gz kernel you see in your
grub config; it is what sits in ring0; it mediates access to the cpu,
to ram, and (loosly) the pci bus. all other domains
run under the hypervisor. the Dom0 is a privliged guest domain that has
access to send control statements to the hypervisor, and that has access
to the PCI bus. The Dom0 will access real hardware and present
xen disk and network devices to the hypervisor; the hyperviosor then passes
those virtual devices out to the unprivliged domains, the DomU.)
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