Re: [patch 4/6] ps3: Disk Storage Driver

From: James Bottomley <redacted>
Date: Fri, 15 Jun 2007 16:28:03 -0700

On Fri, 2007-06-15 at 16:08 -0700, David Miller wrote:

quoted

From: James Bottomley <redacted>
Date: Fri, 15 Jun 2007 15:40:42 -0700

quoted

On Fri, 2007-06-15 at 14:19 -0700, David Miller wrote:

quoted

Another quirk I have to deal with is that under LDOMs you
can export full disks and also just slices.  So I'll have
to get down into the partition machinery to support that
somehow.

For this, it sounds like you might find nbd a more enticing
proposition ... it already is partition independent and is basically a
block to net socket exporter.

That's not gonna work, it's a totally different model.

I have a predefined protocol over hypervisor provided "channels" and
page flipping also done by the hypervisor for the bulk data transfer.
For the client side I cannot change the hypervisor nor the server
speaking on the other end.  And when I do write a server I do want
it to be able to speak to all of the existing clients.

There's SCSI command pass through as well, as I keep mentioning as
it's an important reason I don't want to go with any of the non-SCSI
solutions (other than perhaps ATA) being suggested.

Then sure, use SCSI ... the ibmvscsi client originally talked to some
type of hypervisor interface too before IBM extracted it and open
sourced the server.  If actual SCSI commands are going in somewhere ...
be it a real device, a RAID firmware emulation or a hypervisor input,
then I'm happy with the driver being in SCSI.

For normal block I/O it's just raw copies over the provided protocol.

But the service exports a service by which raw SCSI commands can be
sent, for things like disk fault probing and stuff like that.  It's
not for block I/O, it's for "all the funny stuff" scsi comands are
used for outside of actual data transfers.