multi-path IO in SCSI mid-layer

Patrick Mansfield
2001-06-26T18:02:36Z

Hi -

I'm interested in multi-path IO in the linux scsi mid-layer.

Are there developers working on changes to the scsi layers/interfaces?
I've seen references about such work, but no details.

Anyone else interested in or working on multi-path IO in the mid-layer?

I've looked at the code as to what changes might be required, and did
a simple prototype to issue IO requests using multiple paths for one device -
configuring one device in with multiple paths using SCSI INQUIRY page 0x83,
and selecting a path (just round-robin) at scsi_submit_cmd() time.

But, a decent multi-path IO implementation requires significant changes
to the current linux scsi interfaces/structures - especially where no
functional interfaces exist, such as the direct references to Scsi_Device
host, and Scsi_Host host_queue.

--
Patrick Mansfield
patman@sequent.com
patman@us.ibm.com