[Debian-User] Xen Dom0 and DomU
I put your text below mine. Yes, it does sound neat. Did you do a special compile for the RAID so it was built into the kernel or do you have a hardware raid controller, or what?
Perhaps I am wrong but I think Dom0 should contain (but not with the purpose of executing) all applications that the DomU virtualizations execute. This is one reason why software RAID implementations should be avoided with respect to Dom0 -- the primary Xen system. That way Dom0 (which is the basic Xen virtualization) can be used to check out integrity issues with a flaky DomU. This means that these applications need to initially be tested on Dom0. Often the DomU virtualization will be heavily modified or at least tuned whereas Dom0 can demonstrate that the application out of the box works even if the virtualization does'nt or has stopped working properly. This is important when doing any kind of development where the development effort extends from the basic package resident on Dom0. Personally, I think DomU (the secondary systems) virtualizations exist only for the purpose of dedicated servers and applications operating on a minimal code base. The rule is one application per virtualization. Whereas, I see Dom0 inflated and fat like an overfed pig serving not only as the Xen base architecture but also upgradeable (where this does not have to be the case with the DomU -- secondary virtualizations).
There are of course those that would disagree but debate on these issues will clarify these issues over time.
Thanks for your virtualization details -- have fun!!! Yes, it is all yours!
Thanks, Ted -- hope there were no typos because a typo on this subject can be the opposite of what is intended when U is accidentally used for 0. That's why I keep sticking in comments regarding the primary versus the secondary systems.
Here is what you said:
"I now have the following setup:
Dom0 P4 based server with approx 450 gigs of RAID-5 storage in one big
lvm volume-group alongside .5gig RAID-10 swap and RAID-1 / partitions
(spread over 4 disks). I know its a monster for a home server, but
hey, its mine-all-mine baby!
Okay, Dom0 is on the LAN and serves up music, video, photos and pulls
backups (rdiff-backup with password-less login) from the other
machines on my LAN.
I have two DomU's. DomU1 is my firewall running a standard 3 interface
shorewall installation and dhcp/dns for the LAN. My net interface is
brought up directly in the DomU by hiding it from Dom0
(pciback-hide). It gets ip from my cable modem. My loc interface is
bridged with eth0 in Dom0 to put the server (bigmomma) and my local
machine all on the same subnet (192.168.1.0). My DMZ interface is a
"phantom" bridge connecting DomU1 (firewall) to DomU2 (mail). That's
the hard part, getting that bridge configured. DomU2 is my mail server
and uses fetchmail to pull mail from various accounts, processes it
through clamav, and spamassassin finally dumping it to individual
users procmail recipes for storage in maildirs and served up by
dovecot imap. "
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