Xen project Mailing List

On Tue, Jan 17, 2017 at 7:57 PM, Kuba <kuba.0000@xxxxx> wrote:

W dniu 2017-01-16 o 17:06, G.R. pisze:

Hi all,
I'm trying out the storage driver domain feature

Hi

A while ago, with a great deal of help from Roger Pau Monné, I managed to use FreeBSD domU as storage driver domain to provide storage for other domUs.

The main difference is that it didn't require any network-based protocol (iSCSI etc.) between the domains.

Typically your domU's frontend driver is connected to a block device inside dom0 via dom0's backend driver. But Xen has the ability to connect your domU's frontend driver directly to the backend driver of another domU. In short, you can create a storage driver domain, create a block device inside it (e.g. a zvol) and than create another domU using this block device directly, just as if it was provided by dom0.

Here you can find the steps that should get you started. It was a while ago and required to apply a patch to Xen; I don't know what's its status right now, but since FreeNAS is based on FreeBSD, it might be worth to take a look:

https://lists.xenproject.org/archives/html/xen-users/2014-08/msg00003.html

Hi Kuba,

The information you provided sounds fairly interesting! Thank you soooo much~~

Strangely enough, the same patch quoted in your link is still relevant and required after 2.5 years and 4 major release!

Roger, do you meant to submit your patch but some how get it lost?

Without the patch:
frontend `/local/domain/5/device/vbd/51712' devtype `vbd' expected backend `/local/domain/0/backend/qdisk/5/51712' got `/local/domain/1/backend/vbd/5/51712', ignoring
frontend `/local/domain/5/device/vbd/51712' devtype `vbd' expected backend `/local/domain/0/backend/qdisk/5/51712' got `/local/domain/1/backend/vbd/5/51712', ignoring

With the patch:
Using xvda for guest's hda
******************* BLKFRONT for /local/domain/9/device/vbd/51712 **********

backend at /local/domain/1/backend/vbd/9/51712
156250000 sectors of 512 bytes
**************************
blk_open(/local/domain/9/device/vbd/51712) -> 5

However, I do NOT have the luck as Kuba had for a working system. (My first attempt yesterday at least give me a booting screen :-))

What I see is the following errors:
Parsing config from ruibox.cfg
libxl: error: libxl_dm.c:1963:stubdom_xswait_cb: Stubdom 9 for 8 startup: startup timed out
libxl: error: libxl_create.c:1504:domcreate_devmodel_started: device model did not start: -9
libxl: error: libxl_device.c:1264:device_destroy_be_watch_cb: timed out while waiting for /local/domain/1/backend/vbd/9/51712 to be removed
libxl: error: libxl.c:1647:devices_destroy_cb: libxl__devices_destroy failed for 9
libxl: error: libxl_device.c:1264:device_destroy_be_watch_cb: timed out while waiting for /local/domain/1/backend/vbd/8/51712 to be removed
libxl: error: libxl.c:1647:devices_destroy_cb: libxl__devices_destroy failed for 8
libxl: error: libxl.c:1575:libxl__destroy_domid: non-existant domain 8
libxl: error: libxl.c:1534:domain_destroy_callback: unable to destroy guest with domid 8
libxl: error: libxl.c:1463:domain_destroy_cb: destruction of domain 8 failed

Attaching the config and qemu-dm log for triage purpose.

Some time later I managed to set up a "true" storage driver domain using PCI passthrough to assign SATA controller directly to the driver domain and used that domain to provide storage for Windows-based guests. It worked flawlessly. I believe this idea might be interesting to you too.

Actually my domU NAS has being running with PCI passhtroughed SATA controller for 4 years.

It's just that the storage driver domain was NOT available in version 4.1.x ~ 4.3.2 when I built my box.

Regards,
Kuba

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxx
https://lists.xen.org/xen-users

Re: [Xen-users] HVM domU on storage driver domain