Hi,
I'm trying to understand how a Solaris domU accesses either a file-
back or device-backed VBD images. By "accesses" I simply mean how a
VBD appears to the domU.
Looking at http://opensolaris.org/os/community/xen/docs/specs.html
"...
DomU Disk Space Requirements
Solaris supports both file-backed and device-backed VBD images. File-
backed images are files containing the UFS file system image. File-
backed images are accessed by mounting the file using the loopback
file driver described in the lofi(7D) man page. Device-backed images
can be stored in a disk partition or a Solaris Volume Manager device.
Solaris Volume Manager soft partitions are the recommended method for
storing domU images for the flexibility and performance advantages
they have over physical disk partitions and file-backed images.
..."
Q1. My understanding is that when running virt-install using -l
<path>.iso that lofi will be used to mount the iso image used by virt-
install. However how is the file-backed VBD image say /export/
solarisPV/root.img made available to the guest domain. I'm interested
if lofi is somehow used after the file-backed VBD is created, i.e.
once the install is complete does domO somehow export via lofi the VBD
image to the domU.
Q2. As a follow on to Q1. how is a device-backed VBD image made
available to the domU.
Looking at http://opensolaris.org/os/community/xen/docs/developers/
"...
In a paravirtualized domU, each driver has a "front end," which is
present within the domU, and a "back end," which runs in dom0. These
are referred to as PV drivers. The front end driver takes standard
requests from Solaris and forwards them to the back end driver. The
back end driver executes the request on the physical hardware and
passes any result back to the front end driver, which then notifies
Solaris of the request's completion. Since the driver is explicitly
hypervisor aware, it is able to work with the hypervisor and the back
end driver to deliver much better performance than a driver in a fully
virtualized environment.
..."
Q3. Is lofi used by these PV drivers?
Many thanks
Neil
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