Hanging during boot

As a followup to the previous post (and this one before that)...

It still takes 4-5 hours to boot.... specifically, dmesg shows that this took 4 hours...

Jul  7 08:15:32 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 0 irq 0xe vector 0x90 ioapic 0x4 intin 0xe is bound to cpu 2

(previous line [cdrom] was fine... rest are not)
Jul  7 08:15:32 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 3
Jul  7 08:15:32 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 0
Jul  7 08:15:40 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 3
Jul  7 08:15:57 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 0
Jul  7 08:15:57 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 1
Jul  7 08:15:57 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 2
Jul  7 08:15:57 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 3
(repeat and repeat and repeat)

Jul  7 12:21:13 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 0
Jul  7 12:21:14 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 1

(system becomes usable here)
Jul  7 15:24:19 serveris xpv_psm: [ID 805372 kern.info] xVM_psm: ide (ata) instance 1 irq 0xf vector 0x98 ioapic 0x4 intin 0xf is bound to cpu 3


Any thoughts why a non-existant IDE device is polled for 4 hours during boot?  Or why after finally booting, it is *still* doing it?

UPDATE: Bug submitted

Server Died

So I got home last night to find the server had power but was not responding (mouse, keyboard, ssh, anything). I tried rebooting, but it kept handing at "Hostname: serveris" and wouldn't go any further (even in single-user mode). I saw some chatlogs online that suggested adding '-k -a -d verbose' and using '/dev/null' to the answer of any questions (like /etc/system replacement)...

I tried that and got this far (see left)...

Looking around some more, I saw that if I changed the '-k' to '-kd' it would drop it into debug mode. At that point, I did the following:



[0] moddebug/W 80000000
[0] :c

This allowed me to see a few more details.... (sorry for the blurriness of the pic - it was about 3am)

After trying to find anything online that would help (and the IRC channel) I finally said screw it and decided I would reinstall opensolaris on the root mirror.

I downloaded the USB version of OpenSolaris 0906 111a, but evidentially my quad core machine does not have the option of booting from USB (WTF?). I reburned the CD version and installed it. One thing that confused me is that although my old system was 10/08 upgraded to 111a and the new version was supposed to be 0906 111a, it now says 101b.

Trying to boot the new one, it again hung. At a different position, but... I was starting to think it was a hardware problem. I let it try to boot overnight and the next morning it was finally at the login prompt... with the old install.

The logs showed that it had tried to load the Belkin UPS a few steps after where it locked up, so I unplugged the UPS. I went ahead and applied all updates and rebooted. It took about 5 hours for it to finally boot again (though it did). It still says I am using 101b and that there are no new updates.

The xVM instance is there and I was able to start it. The whole root zone however is gone. The ZFS partition is there, and empty. zoneadm doesn't show anything but global. So, I am going to try to recreate the global zone, but... I still don't know what happened. I am also concerned that it currently takes about 5 hours to boot.

Auto-starting domUs

Assuming domU is named... ummm... 'domU'
# vi `virsh dumpxml eoti | grep -i uuid | sed 's/\s*<uuid>/\/var\/lib\/xend\/domains\//g;' | sed 's/\s*<\/uuid>/\/config.sxp/g'`

change: (on_xend_start ignore)
to: (on_xend_start start)

Setting up xVM....

It was a long and tedious process, but I got it working (on my work machine)... well, actually, it wasn't so bad once this was resolved [which took about 2-3 days to figure out]. While working on that, I also installed SUNWxvmhvm as it appeared to be the only xVM one not installed according to the Package Manager.


The first step was to download the ISOs. I ended up downloading both sol-10-u6-companion-ga.iso and sol-10-u6-ga1-x86-dvd.iso, though I haven't gotten around to using (or even looking at) the companion cd.

I played around a few times until I figured out how I wanted this done. I decided the original domain was going to be used as a starting point to clone from, and not as a domain to run; so some of the names seem a little overboard early on. I used this page for a lot of the details of what to do.

The next step was to create a volume.
root@eris:/rpool/vm/iso# zfs create -V 16G rpool/vm/sol-10-u6-ga1-x86.zvol
This creates /dev/zvol/dsk/rpool/vm/sol-10-u6-ga1-x86.zvol.

Using virt-manager to create the domain:
name: sol_10_u6_ga1_x86
virtualization: full
iso: /rpool/vm/iso/sol-10-u6-ga1-x86-dvd.iso
os type: Solaris
os variant: Sun OpenSolaris
disk: /dev/zvol/dsk/rpool/vm/sol-10-u6-ga1-x86.zvol
nic: shared eg1000g0
mem (min): 1024
mem (max): 1024
VCPUs: 1

During the installation, Solaris and Option 4 (to allow for a ZFS root).
Once it was installed, I rebooted and verified that it worked. I shut it down.
root@eris# zfs snapshot rpool/vm/sol-10-u6-ga1-x86.zvol@FreshInstall
root@eris# zfs list -t snapshot -r rpool/vm/sol-10-u6-ga1-x86.zvol | grep -v auto-snap
(the second step was to verify that it worked)

Logged into the domain (using virt-manager)
root@sol_10_u6_ga1_x86# sys-unconfig
This halts it, but through trial and error I found that I need to hit a key to get it to start restarting THEN hit the shutdown button on xVM so that it is NOT running.
root@eris# zfs snapshot rpool/vm/sol-10-u6-ga1-x86.zvol@Unconfigured
root@eris# zfs clone rpool/vm/sol-10-u6-ga1-x86.zvol@Unconfigured rpool/vm/eris-vm1.zvol
root@eris# zfs snapshot rpool/vm/eris-vm1.zvol@Unconfigured

root@eris# zfs list -t all -r rpool/vm/sol-10-u6-ga1-x86.zvol | grep -v auto-snap
NAME USED AVAIL REFER MOUNTPOINT
rpool/vm/sol-10-u6-ga1-x86.zvol 22.1G 51.1G 5.93G -
rpool/vm/sol-10-u6-ga1-x86.zvol@FreshInstall 0 - 5.89G -
rpool/vm/sol-10-u6-ga1-x86.zvol@Unconfigured 0 - 5.93G -
root@eris# zfs list
NAME USED AVAIL REFER MOUNTPOINT
rpool 37.7G 35.1G 50K /rpool
rpool/ROOT 7.64G 35.1G 18K legacy
rpool/ROOT/opensolaris 5.85G 35.1G 5.52G /BE/opensolaris
rpool/ROOT/opensolaris-1 776M 35.1G 5.52G /BE/opensolaris-1
rpool/ROOT/opensolaris-2 1.03G 35.1G 5.77G /tmp/tmpFWvL5Q
rpool/dump 1.93G 35.1G 1.93G -
rpool/export 1.35G 35.1G 19K /export
rpool/export/home 1.35G 35.1G 19K /export/home
rpool/export/home/malachi 1.35G 35.1G 423M /export/home/malachi
rpool/swap 1.93G 37.0G 16K -
rpool/vm 24.9G 35.1G 2.78G /rpool/vm
rpool/vm/eris-vm1.zvol 0 35.1G 5.93G -
rpool/vm/sol-10-u6-ga1-x86.zvol 22.1G 51.1G 5.93G -

Then to create the domain configuration:
root@eris:/rpool/vm# virsh dumpxml sol_10_u6_ga1_x86 > sol_10_u6_ga1_x86.xml
root@eris:/rpool/vm# cp sol_10_u6_ga1_x86.xml eris_vm1.xml

Edit the new eris_vm1.xml:
1. replace the domain name
2. remove the UUID line
3. replace the zvol location (from sol_10_u6_ga1_x86.zvol to eris_vm1.zvol)
root@eris:/rpool/vm# virsh define eris_vm1.xml

Boot into the new domain and configure it. Reboot and make sure the internet works. Shut it down.

root@eris# zfs snapshot rpool/vm/eris-vm1.zvol@Configured

That's it. It's now bootable and the original one is still available to clone another from.

hvm not available

The work machine is a Dell OptiPlex 755 with an E8400 cpu and BIOS A11. I couldn't figure out why both 'xm info' and 'virt-install' both showed as it not having virtualization support. I tried turning it off and back on (in the bios), etc.

Turns out (thx to this thread) it just required turning OFF 'Trusted Execution' in the BIOS.

Xen and VNC

When reading through this blog entry, I noticed this bit and so did that:
set the xen vnc password ( http://blogs.sun.com/shalon/entry/virt_install_demo )
# Set the prop in xvm which is used to initialize the console password
soe-x4600m2-2:root> svccfg -s xvm/xend setprop config/vncpasswd=astring:\"bacon\"
# Restart xend
soe-x4600m2-2:root> svcadm refresh xvm/xend; svcadm restart xvm/xend
I am not sure whether it is really required. I am uncomfortable that ANY user can read whatever password root sets.

virt-manager

I upgraded to svn_96 (see last post) in order to install virt-manager. In my previous build (svn_94) the Package Manager didn't work - but in svn_96 it is working again. I did a search for 'virt' and chose to install the one xVM package that appeared to be missing...

At the end of the install, it appeared to have hung at 100%. I went to the command line and did 'pkg info SUNWvirt-manager' and it said it was installed, so I just closed the installer window. I reopened the Package Manager and verified it was installed.

Now to try to figure out how to use it =)

Installing xVM

I used this as a starting point to get Xen running.

1. Install the base xVM

pkg install SUNWxvmhvm
pkg install SUNWvirtinst
pkg install SUNWlibvirt
pkg install SUNWurlgrabber

2. Configure GRUB (I did this step completely different)

pfexec gedit /rpool/boot/grub/menu.lst

add:

title   ... xVM
 findroot (pool_rpool,0,a)
 kernel$ /boot/$ISADIR/xen.gz
 module$ /platform/i86xpv/kernel/$ISADIR/unix /platform/i86xpv/kernel/$ISADIR/unix -B $ZFS-BOOTFS
 module$ /platform/i86pc/$ISADIR/boot_archive
 bootfs rpool/ROOT/opensolaris-1

3. Reboot into new configuration

4. 'uname -a' should contain 'i86xpv'

5. Startup the services

svcadm enable store
svcadm enable xend
svcadm enable console
svcadm enable domains
svcadm enable virtd 

6. Make sure they are running

malachi@serveris:~# svcs | grep xvm
online         19:34:15 svc:/system/xvm/store:default
online         19:34:22 svc:/system/xvm/xend:default
online         19:34:24 svc:/system/xvm/console:default
online         19:34:29 svc:/system/xvm/domains:default
online         19:34:33 svc:/system/xvm/virtd:default
 

Now to figure out how to do the domU :)

Solaris*VoIP

Consider whether to use the Solaris version of Asterisk or Linux version (either way, it will be running in Xen)

Possible Plan

Ok, what if we start with plugging raw drives into the network, fronting as iSCSI Targets (possibly using embedded netbsd)...

Then the Solaris dom0 sets these up as Raid-Z.

Solaris then exports a NFS root for each domain. In fact, we could also export CDROM images and such over NFS so that the various OSes could have access to them.

At this point we would either have a small grub floppy image that would do network boot; or we have Xen boot the domU directly over the network. In either case, the plan is the same, have the OS run 'diskless' over NFS (with rw permissions)... If they have access to change which kernel grub points to, probably better.... so what if we have a small local grub image that points to a remote NFS grub image that is local to that filesystem... and thus they could change which kernel image, but not where it is...

Anyways, then, if we want to increase storage capacity, we add a drive to the network (iSCSI) and tell ZFS to add it to the pool... voila, all the domains have more space.

And if we want to back up a domain, we can take a snapshot and clone, etc.... I see us taking a snapshot at say 12:01am on monday, then incremental snapshot every day; thus we can rollback up to a week... although, probably need to maintain 2 weeks if we want to restore 1 -- otherwise every monday when we kill the primary full snapshot, all the incrementals become useless...

And if there is a hardware failure, Raid-Z should autorecover and provide means for me to fix it.

And if we need a test domain, we should be able to snapshot/clone (although booting with the same network parameters could be a problem).

And we should be able to write a tool (web based) that they can run in their own domain to request that we revert back to a previous snapshot...

And if we need to, we can specify quotas or reservations on a per domain or even on a per directory...

And although NFS should cause some overhead, since it is on the same physical server, I doubt it will even talk to the network...

And if we ever need to offload one of the domU to a different server, it should be extremely simple since we'd only need to move the Xen configuration and the tiny grub floppy image.


Overall I am liking this idea. Not sure how well it will work, but I guess I should start looking at hardware for it.

BTW: The Solaris dom0 needs redundancy too. I figure that what we would do is have a small mirrored root to boot Solaris -- but the dom0 needs to be the one in charge of the Raid-Z, so...

How to setup Xvnc with Solaris domU

How to setup domU in Solaris

Thoughts... ie: What should I do?

So as I investigate things like Sun servers, OpenSolaris, ZFS/Raid-Z, iSCSI, Embedded NetBSD, etc etc... I start thinking that perhas a better approach would be to start off with a list of requirements... It is a little late to "start" there, but, what the hell...

* We do not want a repeat of the data wipeout we got a year ago... As such, if one domain gets hacked, it can not take down the rest of the domains.
- I had been planning on using Jail to alleviate this problem, but at this point I think our best bet is Xen
- While many OSs support Xen domU, many fewer support Xen dom0.

* Also, if a domain gets hacked and wiped out, we need a backup to restore from.
- ZFS Snapshots (maybe full weekly and incremental daily) seems like a good solution for this
- SVN might be a good solution to this
- It might be good if there was a way to automate this (ie: allow the root user to do it instead of emailing me)

* We want to get disk redundancy, while keeping cost and maintenance low.
- RAID-0 gives us the redundancy, but at a fairly high cost. The current 1TB gives us less than 500GB this way.
- RAID-5 could be acceptable, as long as we could fix the system if the root partition were the one to screw up
- ZFS and Raid-Z seem like excellent options to provide the redundancy and automatic corrections

* Each domain should be able to have it's own root user and OS.
- Jail could have provided for this, but seems very buggy ('man man' in a jail crashed the entire OS)
- Xen should allow for this fairly easy. As such, the base OS really doesn't do anything other than launch the domUs.

* If multiple OSs share a base OS, it would be nice (though not required) if we were able to not waste a lot of duplicated space
- Unionfs is ideal for this. Not sure how easy it is to use with Xen
- At some point, it has to be better to have a full copy (like if they upgraded every single app)

* It would be preferable if all OS's could run unmodified, thus allowing us greater flexibility and choices
- Intel VT or AMD-V technology. If we are planning on doing any RSA work on any domain, it can't be the Intel option. So probably an Opteron 2xxx (or 2).

* If we run low on drive space, it should be fairly simple to add more
- ZFS is supposed to allow for this with 'zfs add'
- We *could* do separate drives for each domain, but that would waste a lot of drive space
- iSCSI might be a better option than internal drives for this. Instead of running out of hard drive bays, we'd just have to worry about running out of ethernet ports -- which realistically, is much easier to come up with more of. ** SEE BELOW

** iSCSI Thoughts:
- IDEALLY, I would have a set of cheap 250GB or 500GB drives that host themselves as iSCSI Targets. Then, adding new drives is literally adding another drive to the network.
- We could, in theory, run Solaris or NetBSD to easily provide iSCSI Targets to the network - but then we have to wonder why we are creating a separate box to host Xen
- If we have multiple iSCSI Targets, which our Solaris(?) box were to RAID-Z together, we could also have extra iSCSI Targets that VMWare and/or other hardware could use directly (even Windows)
- If we have multiple iSCSI Targets, which our Solaris(?) box were to RAID-Z together, the Solaris box could provide the pool as a iSCSCI Target to other devices/OSes
- If we were to have Solaris running RAID-Z directly on the iSCSI Target (ie: providing ZFS pools as iSCSI Targets), then separate Xen domUs could point to these iSCSI Targets for their primary data storage and POTENTIALLY get the ZFS benefits regardless of their OS (snapshots, error-correction [at least from hardware errors], etc)
- In theory, if we could come up with mini embeddable systems that could boot from iSCSI Targets, then we could do away with Xen entirely and just have a little device on the network for each domain... this might be overkill
- Note: Can Solaris boot off iSCSI?

Linux Xen Links from Lee

http://howtoforge.com/virtualization_with_xenexpress

http://howtoforge.com/debian_sarge_xen_3.0.3

EMail conversation with Sun

I received this email....

Hi Malachi,

Thank you for visiting the web chat forum on the Sun website yesterday, when you expressed interest in the Try and Buy promotion being currently run by Sun.

You mentioned that you are deciding which machine you will trial on the promotion - excellent! You will see the full list of products on the promotion at www.sun.com/tryandbuy

You can email me with any questions that you may have, or you can visit our team at the web chat forum. Here's some additional information on the Try and Buy promotion, which you may find useful:

When you receive the Server on the Try and Buy promotion you will also receive a Welcome Pack.
Inside the Welcome Pack you will find-
1. A Quick Guide to Installation.
2. Access to Tuning and Optimization documentation.
3. Access to an online portal and forum for system and application tuning hints and tips.
4. Access to Sun's performance engineers.
5. All of the latest patches and configuration files for the system on the portal.
Additional options for purchase are available for system ready and business ready services.
The Solaris 10 Operating System and other software provided with the system is covered under the Warranty support during the Try and Buy period.


Best Regards

Mark Cradock
Sun Microsystems
Tel: + 353 (0)599136768
mark.cradock@your-sun.com
www.sun.com

My response:

Hi Mark,

I am debating the Sun Fire X4200 or the Sun Ultra 40 Workstation. Perhaps it would be better for me to explain the intended usage and get your feedback.

First, a little background. We had a FreeBSD box running for about 4 years without reboot. As is probably obvious from that statement, we were behind on the security updates. While we were hosting multiple domains, they were not in Xen or Jail or anything. On Christmas eve a year ago, a hacker from a Polish cable isp hacked in through one of the user accounts and wiped out the entire system. Because of this, I decided this time that I wanted to ensure that the various domains stay secure even if one is compromised.

We bought the latest top-of-the-line Asus, AMD, etc. Unfortunately, AMD lied about the capabilities of the board. They said it was capable of RAID-5 on SATAII, but in actuality it is capable of RAID-5 OR SATAII. Then we installed FreeBSD-CURRENT, and found out it doesn't support RAID-5 yet. Needless to say, it has been a hassle.

So we are debating buying a Sun server and running Solaris on it. My expectation is that there should not be any driver compatibility problems at that point.

So long story not so short -- we are looking at trying to run a bootable RAID-Z (yes, I know that requires some tweaking, but I want to ensure that the boot is also recoverable) with a Xen Dom0. On top of that, we want to allow each domain to run its own OS (whichever they choose, thus prefer AMD-V) as a DomU. Based on this, I think that each DomU would get the advantage of Raid-Z on the underlying filesystem, even if they didn't know about it directly, and regardless of which OS they are running.


Do you have any thoughts, concerns, or questions?

Malachi

A followup:

Hi Malachi,

First of all, sorry to hear about the experiences you've had with the FreeBSD and Asus! Not good.

Secondly, one of the reasons for the Try and Buy promotion is that you can test the capabilities of each machine prior to actually buying it. I'm sure that you will have a positive experience and benefit from this.

I would recommend that we assign a server specialist to you, that can be available prior to your choice of machine, and also be available for you right through the trial process to assist you in your testing, additional components, adjustments in configurations, etc. Would you have a
contact number that we can call you on?

Best Regards
Mark Cradock
Sun Microsystems
Tel: +
353
(0)599136768
mark.cradock@your-sun.com
www.sun.com

So the rest will most likely be via phone.

Chat with agent about Sun Try and Buy Products

Please wait while we find an agent to assist you.
You have been connected to Brenda Byrne.
Brenda Byrne: Welcome to Sun Microsystems. How may I help you?
Malachi de AElfweald: Try 2.
Brenda Byrne: Sorry about you getting pushed off a moment ago
Malachi de AElfweald: Hi Brenda. I have a question about Try and Buy products.
Brenda Byrne: Sure - go ahead!
Malachi de AElfweald: I am looking at replacing my server with one to run Solaris (or OpenSolaris), Raid-Z and Xen
Brenda Byrne: ok
Malachi de AElfweald: I assume that the Try and Buy products would all be 100% compatible with Solaris and OpenSolaris, correct?
Brenda Byrne: yes, of course
Malachi de AElfweald: How does the Try and Buy program work?
Brenda Byrne: You can simply receive one of the listed Sun machines on trial, no questions asked, for 60 days, with shipping costs provided by Sun, and at the end of the 60 days, or prior to then, make a choice to keep the machine....or buy it!
Brenda Byrne: Would you be trialing a machine on behalf of a company, or in a personal capacity?
Malachi de AElfweald: Company
Malachi de AElfweald: And do they come with the OS preloaded, or do I install it?
Malachi de AElfweald: Also, is there a subscription fee, or just a one-time cost to purchase?
Brenda Byrne: OS is preloaded
Brenda Byrne: there is a one-time cost to purchase the machines
Brenda Byrne: if I understand you correctly
Malachi de AElfweald: so, for example, it would come with... Solaris10? no subscription/support costs for it?
Brenda Byrne: Yes - they come with Solaris 10 - which is a free operating system anyway.
Brenda Byrne: But no, Solaris 10 customer support does not come provided with the machine
Malachi de AElfweald: available but not required?
Brenda Byrne: There is a fee for signing up to customer support for Solaris 10 (which is not required)
Brenda Byrne: Solaris 10 customer support fees start at $10 per month
Brenda Byrne: What kind of a machine are you thinking of trialing?
Malachi de AElfweald: kk. and is there a way to specify how we want it configured? ie: bootable RAID-Z
Brenda Byrne: yes
Malachi de AElfweald: ok. it all sounds pretty good. I guess at this point I just need to figure out which machine I want.
Malachi de AElfweald: is there anything else I should know?
Malachi de AElfweald: any requirements to qualify or anything?
Brenda Byrne: Nope...except that it is on behalf of your company, and is delivered to your company address
Brenda Byrne: What kind of applications would you test on it?
Malachi de AElfweald: That's fine.
Malachi de AElfweald: A year ago, a polish hacker wiped out our FreeBSD box. everything. multiple domains. I told the FBI, but they didn't even ask what the IP address was.
Malachi de AElfweald: So, I am looking at replacing that server with a new one.
Malachi de AElfweald: Expected usage is that it is going to be a Xen Dom0 and run each domain as a DomU.
Malachi de AElfweald: Primarily, I am a java developer - but that won't really matter since each domain will have its own OS
Malachi de AElfweald: Ok, I think I have all the information I need. Just need to try to decide which machine to go with.
Malachi de AElfweald: Thank you for your assistance.
Brenda Byrne: no problem.
Your session has ended. You may now close this window.

Solaris + Xen

Here is the Xen forum at OpenSolaris' website.
Installation instructions for Solaris dom0/domU
And one persons' experiences and notes trying to do so

Xen Info

Vnets - Domain Virtual Networking

Unmodified Guest Domains

FAQ

Wiki

UnionFS on Xen

Consoles:
Econolism
XenMan

Xen Images:
Jailtime.org
Asterisk@HOME 2.8

Alternative Storage Mechanism?

One other idea we COULD do is have a minimal Xen domain0 server, then run all the domainU off of something like this. While slower, that would give us 1TB of RAID5... but we could easily use more than one ;) Thus easier to expand... not sure...

Xen: Current OS Compatibility

Xen 3.0

Operating System	Runs as Dom0 (host os)	Runs as DomU(guest os)
Linux 2.6	Yes	Yes
NetBSD 3.0	No	currently broken? Actively being worked on
FreeBSD 5.3	No	currently broken? Actively being worked on
FreeBSD 7-CURRENT	no	can be patched; works. see http://www.fsmware.com/xenofreebsd/7.0/
Plan 9	No	currently broken?
ReactOS	No	planned, development stalled
Solaris 10	Unknown	Yes
Un-Modified OS	No	Initial support for unmodified guests when using Intel VTX hardware, e.g. Windows