Re: [PATCH 3/3] nvme-multipath: add "use_nonoptimized" module option

[Hannes Reinecke <hare@suse.de>]

On 9/25/23 18:31, Ewan D. Milne wrote:
> Setting nvme_core.use_nonoptimized=true will cause the path
> selector to treat optimized and nonoptimized paths equally.
> 
> This is because although an NVMe fabrics target device may report
> an unoptimized ANA state, it is possible that other factors such
> as fabric latency are a large factor in the I/O service time.  And,
> throughput may improve overall if nonoptimized ports are also used.
> 
> Signed-off-by: Ewan D. Milne <emilne@redhat.com>
> ---
>   drivers/nvme/host/multipath.c | 22 +++++++++++++++++++---
>   1 file changed, 19 insertions(+), 3 deletions(-)
> 
No. Please don't.

There's a reason why controllers specify paths as 'active/optimized' or 
'active/non-optimized'. If they had wanted us to use all paths they 
would have put them into the same group.
They tend to get very unhappy if you start using them at the same time.
(Triggering failover etc.)

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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