performance: domU in disk image or netboot from dom0 ?

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi,

> I was wondering what was better (regarding performance)
between using
> disk images for domU and just "netbooting"
them from dom0 ?

I have no hard data on this as I haven't tested it. But
both "work  
fine" for a setup with a dozen [not too heavily
utilized] VMs on a  
single physical machine.

> My current configuration is:
> - every dom running NetBSD
> - system and pkgsrc in disk images (4Go)
> - data accessed by domUs from dom0 via NFS.
>
> My thinking configuration would be:
> - every doms running NetBSD
> - system, packages and data accessed by domUs from dom0
via NFS/ 
> netboot.
>
> any pros/cons ?
>
> Going further, as every domUs (or at least 99%) will be
NetBSD's, what
> about using a single NFS shared system/packages via NFS
with a  
> layer for
> conf and temp files.
> Something like:
> domU1:
> 	dom0:/exports/domUs	/		nfs
> 	dom0:/exports/domU1	/mnt/specific	nfs
> 	/mnt/specific		/		union
> domU2:
> 	dom0:/exports/domUs	/		nfs
> 	dom0:/exports/domU2	/mnt/specific	nfs
> 	/mnt/specific		/		union
>
> binary updates are done (once) in dom0:/exports/domUs.
> each vmachine has it's own conf in
dom0:/exports/domU*.
> sounds crazy ?

Yes 

I think you'll spend more effort fighting the standard
setup than it  
is worth.

I ended up with sharing /usr/share + /usr/X11R6 + /usr/pkg
via NFS  
and the rest in machine specific images. That brought down
the size  
of the individual images to less than 200MB. But this is
because I  
need to be able to install local software on each machine.
If that  
isn't needed then you can probably share all of /usr and
shrink  
images to ~50MB.

Local config stuff I manage something à la

for vm in $machines ; do
	copy template.img $vm.img
	mount $vm.img somewhere
	rsync $vm specific stuff into somewhere
	umount
done

Johan

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.0 (Darwin)

iD8DBQFETM3ZKJmr+nqSTbYRAiZvAKCegJOEsN+P+fnhPQJwMpeZINonuACe
Io92
aGwVVr+X44SdJsIrTT+RST0=
=WGnV
-----END PGP SIGNATURE-----