[PATCH 0/6] libata: Support SATA attached via SAS

[PATCH 0/6] libata: Support SATA attached via SAS

[Brian King]

Jeff,

Here is a refresh of my patchset to allow SAS HBAs to use libata to
control attached SATA devices. It should apply cleanly to #upstream.

James,

After our discussion at the storage summit I think I have
a better idea what you are looking for with a SATA transport class.
Unfortunately, the problem I am facing is that I am dealing with a
firmware stack (ipr) which does not expose the physical transport
to the host. The ipr firmware does all the device discovery and reports
a configuration table describing the attached devices, but does not
export any physical topology information. At some point in the future
I hope to be able to extract this information from the ipr firmware
stack and convert ipr to be able to utilize the sas/sata transport class,
but, unfortunately, the firmware interfaces to accomplish this
aren't available at this time.

Brian

-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center

Re: [PATCH 0/6] libata: Support SATA attached via SAS

[Douglas Gilbert]

Brian King wrote:
> Jeff,
> 
> Here is a refresh of my patchset to allow SAS HBAs to use libata to
> control attached SATA devices. It should apply cleanly to #upstream.
> 
> James,
> 
> After our discussion at the storage summit I think I have
> a better idea what you are looking for with a SATA transport class.
> Unfortunately, the problem I am facing is that I am dealing with a
> firmware stack (ipr) which does not expose the physical transport
> to the host. The ipr firmware does all the device discovery and reports
> a configuration table describing the attached devices, but does not
> export any physical topology information. At some point in the future
> I hope to be able to extract this information from the ipr firmware
> stack and convert ipr to be able to utilize the sas/sata transport class,
> but, unfortunately, the firmware interfaces to accomplish this
> aren't available at this time.

Brian,
Does that mean that it doesn't have an SMP pass through?
SMP and the SAS addresses attached to the phys on the HBA
is enough to do discovery in the user space.

Doug Gilbert

Re: [PATCH 0/6] libata: Support SATA attached via SAS

[Brian King]

Douglas Gilbert wrote:
> Brian King wrote:
>> Jeff,
>>
>> Here is a refresh of my patchset to allow SAS HBAs to use libata to
>> control attached SATA devices. It should apply cleanly to #upstream.
>>
>> James,
>>
>> After our discussion at the storage summit I think I have
>> a better idea what you are looking for with a SATA transport class.
>> Unfortunately, the problem I am facing is that I am dealing with a
>> firmware stack (ipr) which does not expose the physical transport
>> to the host. The ipr firmware does all the device discovery and reports
>> a configuration table describing the attached devices, but does not
>> export any physical topology information. At some point in the future
>> I hope to be able to extract this information from the ipr firmware
>> stack and convert ipr to be able to utilize the sas/sata transport class,
>> but, unfortunately, the firmware interfaces to accomplish this
>> aren't available at this time.
> 
> Brian,
> Does that mean that it doesn't have an SMP pass through?
> SMP and the SAS addresses attached to the phys on the HBA
> is enough to do discovery in the user space.

Doug,

That is correct. There is no SMP passthru interface. The interface I
am working with basically gives me some very basic information
regarding all attached end devices (which does not include SMP devices).
The information I get for each device includes: 

1. The LUN's SAS address
2. The type of device to aid in HLDD attachment. This could be either
   a SAS device, a SATA device, or a RAID logical device.
3. A bus/target/lun tuple which can be used to map into SPI if the
   host dd wants to. 

If you look in drivers/scsi/ipr.h at struct ipr_config_table_entry,
that might give you a better idea as to what I get back for each
device.

In a future firmware release I should have the firmware interfaces
I need to be able to extract both adapter SAS/SATA phy information
and SAS expander information such that I can move ipr to fit
into the sas transport model. Unfortunately, I don't have this
today.


Brian


-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center

Re: [PATCH 0/6] libata: Support SATA attached via SAS

[Douglas Gilbert]

Brian King wrote:
> Jeff,
> 
> Here is a refresh of my patchset to allow SAS HBAs to use libata to
> control attached SATA devices. It should apply cleanly to #upstream.

Brian,
I hope that libata's ATA PASS THROUGH (16) SCSI command
is wired up as I just checked a new device type '-d sat'
into smartmontools cvs.

Doug Gilbert

Re: [PATCH 0/6] libata: Support SATA attached via SAS

[Brian King]

Douglas Gilbert wrote:
> Brian King wrote:
>> Jeff,
>>
>> Here is a refresh of my patchset to allow SAS HBAs to use libata to
>> control attached SATA devices. It should apply cleanly to #upstream.
> 
> Brian,
> I hope that libata's ATA PASS THROUGH (16) SCSI command
> is wired up as I just checked a new device type '-d sat'
> into smartmontools cvs.

Yes. Any command supported by libata today should also be supported
with this patchset.

Brian

-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center