Re: [PATCH] scsi_transport_spi: Export host width and HBA id

[Douglas Gilbert <dgilbert@interlog.com>]

On 11-06-01 11:00 AM, Hannes Reinecke wrote:
> On 06/01/2011 04:56 PM, James Bottomley wrote:
>> On Wed, 2011-06-01 at 15:18 +0200, Hannes Reinecke wrote:
>>> Currently it's impossible to find out if the host supports
>>> wide SCSI unless you're committed to trawl through syslog.
>>> And it's near impossible to find the actual HBA id, which
>>> is settable for some SCSI HBAs (like aic7xxx).
>>> So export them via sysfs.
>>
>> Um, that's what the the
>>
>> /sys/class/spi_transport/target<x:y:x>/max_width
>>
>> parameter gives you, isn't it?
>>
>> max_width tells you if the HBA/device combination supports wide; width
>> tells you if the device is using it.
>>
> Not quite. You'll only have that parameter if there is a target attached to the
> HBA.
> If there is none you still wouldn't know how far you should be scanning as there
> won't be any indicator in sysfs.
>
> In this case that's an ESX server emulating an sym53c8xx HBA.
> And disks attached to it on the fly.
> If you start up with no disks attached and attach a new disc
> to eg target ID 12 you're stuck.

It is about time that VMware emulated SAS rather than SPI for
virtual storage. Then if something changes, ESX can emulate
a SAS Broadcast(Change) and then smarter SAS HBA drivers will
run their discover process and find the changes.

Doug Gilbert