Re: aacraid driver question

['Christoph Hellwig' <hch@infradead.org>]

On Mon, Aug 25, 2003 at 03:56:27PM -0400, Salyzyn, Mark wrote:
> AifDenMorphComplete is issued after a Morph (ie, adding new driver to an
> existing array to expand it's capacity) has completed. Capacity reduction is
> not typically a side effect, but redundancy can change (RAID-5 to RAID-0).

You managed to get me really confused :)

So AifDenMorphComplete and AifDenVolumeExtendComplete are the same from
the drivers perspective?

Anyway, for those two scsi_rescan_device is thw way to go.  I'll
export it in 2.6.

> A Zero of an array has the side effect of also clearing out the first block
> of the array, and thus the partition table. The management applications make
> this function available, and we must live with it's consequences.

Okay...

> Ok, looks like you've up'd my priority on finding out how to differentiate
> online/offline/clear; sadly AifEnContainerChange was a `catchall' for most
> changes to an array of all sorts. Even more sad is that there are no details
> contained within the FIB and I am otherwise quite nervous issuing commands
> to the adapter to probe the cause. Yes, this makes a case for a user,
> instead of a kernel, daemon to perform this task. I will find a way.

Yikes!

> Are we truly painted in a corner here? The `proc_write' call to the classic
> kernels I did had the side effects of bringing online/offline/changed device
> status up to date; albeit, we had a performance issue when devices went
> offline. A compromise is that offline `will just happen' when someone tries
> to communicate to the ID of the device. What will scsi_add_device do to us
> if the device was there and is no longer accessible? Could we make the pair
> of calls (scsi_add_device + scsi_rescan_device) in the interim?

Well, we could keep the semantics without the proc_write mess by
exporting scsi_scan_host_selected as Mark H. did in the patch that
triggered this thread, but I'd be very unhappy to do that.  We have
the exported scsi_add_device and scsi_remove_device functions to
add/remove a selected lun and if possible at all I'd prefer to use those.

scsi_add_device will return an error it it's not actually present,
but we don't have a way to remove an existing volume going that route
unless we find out whether we really meant offlining it.