Re: Installing a NetBSD DomU on a file-backed disk

[Blair Sadewitz <blair.sadewitz%gmail.com@localhost>]

On Wed, Jun 13, 2012 at 2:42 AM, Manuel Bouyer 
<bouyer%antioche.eu.org@localhost> wrote:
> On Tue, Jun 12, 2012 at 07:39:14PM -0400, Blair Sadewitz wrote:
>> Oh, btw, why does the dmesg list the root device twice?  Also, it
>
> I've not noticed this; maybe it's because there's no disklabel ?


Oh, there is disklabel; it's not a very _good_ one, but it's there:

# /dev/rxbd0d:
type: unknown
disk: Xen Virtual ESD
label:
flags:
bytes/sector: 512
sectors/track: 2048
tracks/cylinder: 1
sectors/cylinder: 2048
cylinders: 20480
total sectors: 41943040
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # microseconds
track-to-track seek: 0  # microseconds
drivedata: 0

16 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:  41943040         0     4.2BSD   2048 16384     0  # (Cyl.      0 -  20479)
 c:  41943040         0     unused      0     0        # (Cyl.      0 -  20479)
 d:  41943040         0     unused      0     0        # (Cyl.      0 -  20479)

Pv-grub, to my astonishment, works with ffs (at least v1) like that.
I have no idea how it would handle anything less straightforward, e.g.
non-zero offsets, ffsv2, etc.  I surmise that being a domu on a netbsd
host is more pleasant ...

I wish there was something I could do about the poor disk performance
besides turning off wapbl.  But whether I turn it off or not, any
other suggestions for better performance [particular to this case]?

Regards,

--Blair