Re: [LSF/MM/BPF TOPIC] Native SCSI multipath support

Mike Snitzer
2026-02-21T17:41:30Z

On Fri, Feb 13, 2026 at 02:19:11PM +0000, John Garry wrote:
> At ALPSS 25 I presented a proposal for Native SCSI multipath support. Let's
> discuss this topic at LSFMM.
>
> The idea for this is that SCSI could natively support multipath, like how
> NVMe host driver does today. It is intended as an alternative to
> dm-multipath support.
>
> I have been working on the implementation and I plan to post patches in the
> next cycle. I am looking at a 3-stage approach:
> a. create a driver-agnostic multipath library, very heavily based on NVMe
> host multipath support.
> The library would support features such as path management, path
> selection/iopolicy, failover recovery, PR, delayed removal, gendisk
> management etc.
> b. switch NVMe over to use this library

I can appreciate that the kernel to userspace interface of DM
multipath is clearly unwanted (hence NVMe multipath and now SCSI
multipath).

But you should really be switching DM-multipath over to using it too;
or at least detailing _why_ the core of DM multipath
(drivers/md/dm-mpath.c) cannot be updated to use this common backend
library.

This line of work makes little sense to me if it just ignores
dm-multipath.

Mike

> c. add native SCSI multipath support based on this common library
>
> Thanks,
> John
>
>
>