Re: [PATCH 3/4] docs: add pvscsi.txt

[Juergen Gross <jgross@suse.com>]

On 03/02/2015 11:16 AM, Olaf Hering wrote:
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> Cc: Ian Campbell <ian.campbell@citrix.com>
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Cc: Jan Beulich <jbeulich@suse.com>
> Cc: Keir Fraser <keir@xen.org>
> Cc: Tim Deegan <tim@xen.org>
> ---
>   docs/misc/pvscsi.txt | 147 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 147 insertions(+)
>
> diff --git a/docs/misc/pvscsi.txt b/docs/misc/pvscsi.txt
> new file mode 100644
> index 0000000..2af050f
> --- /dev/null
> +++ b/docs/misc/pvscsi.txt
> @@ -0,0 +1,147 @@
> +. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
> +PVSCSI
> +
> +== Overview ==
> +
> +PVSCSI allows to assing a "physical" SCSI device from dom0 to a domU. The device
> +is not limited to be a native SCSI device. Everything visible as SCSI device in
> +dom0 can be used. Currently PVSCSI is only available in Linux dom0 and domU.
> +
> +== TODO ===
> +
> +How to do live migration?
> + - pdev will likely be evaluated again on the target host if it came from
> +   domU.cfg. But what about pdev from 'xl scsi-attach pdev vdev'? Its required
> +   to adjust h:c:t:l on the target host.

Use WWN notation? :-)

This was one of the reason the backend should support it.

> +
> +Implement checks for duplicate pdev assignments?
> + - Not sure if SCSI devices can be shared. Will the state be consistent during
> +   concurrent access? Should the host admin assume cooperative access from
> +   multiple domUs?

SCSI does support device sharing. That's the reason for the existence of
SCSI commands like "reserve" and "release".


Juergen