Re: [Xen-devel] [Patch 0/7] pvSCSI driver

[Jun Kamada <kama@xxxxxxxxxxxxxx>]

Steven-san,

On Thu, 28 Feb 2008 11:13:31 +0000
Steven Smith <steven.smith@xxxxxxxxxxxxx> wrote:
> What I don't understand is why you need this at all.  It seems like it
> would make more sense to either:
> 
> a) Hang every LUN off of the same scsi host, or
> b) Give each LUN its own scsi host.
> 
> Is there some reason why you might want to do something like this:
> 
> Host A  -------+----- LUN 1
>                |
>                +----- LUN 2
> 
> Host B  ------------- LUN 3
> 
> i.e. partition the virtual LUNs between multiple hosts in the guest,
> but keeping some of them together?  Perhaps I'm just missing
> something, but I can't think of any use cases which would benefit from
> that, and trying to support it noticeably complicates the frontend.

Can I explain a numbering logic of assigning LUNs to guests?

Basically, each guest looks same SCSI tree as host except for following
two points. 

1.) The "host" in 4-tuples "host:channel:id:lun" on guest may not be
    same as that on host. 
2.) Tree on the guest may be sparse when some LUN doesn't assign to
    the guest.

Therefore, "a1:b:c:d" on host becomes "a2:b:c:d" on guest. (a1 != a2
generally)

I think the numbering logic is same as b) you mentioned above. Is it
right?

Thanks,

-----
Jun Kamada



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