[Bug 271118] [nvme] : drives with more than 16 namespaces are missing some devices with nda driver

From: <bugzilla-noreply_at_freebsd.org>
Date: Fri, 28 Apr 2023 12:06:27 UTC

            Bug ID: 271118
           Summary: [nvme] : drives with more than 16 namespaces are
                    missing some devices with nda driver
           Product: Base System
           Version: CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: florian.millet@laposte.net

Created attachment 241820
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=241820&action=edit
output of nvmecontrol ns allocated

These tests are being done on 24 NVMe drives server on FreeBSD 13.1 with nda
driver, the model of all NVMe drive used is SAMSUNG MZWLJ15THALA-00007.

This model support up to 32 namespaces, so to try it out I created 32
namespaces on the nvme0 controller (which did not work prior to
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=269912) and tried to attach
them all.

What I found is that you cannot have more than 16 namespaces on the same
controller that can attach. If you have more they are not presented to the OS
and not present in /dev

It seems like a weird limitation based upon old SCSI standard. If these drives
support 32 namespaces each (and some drives can have more), we should be able
to access all of them.

I did not see any sysctl or tunable that could help.
Is this behavior as designed or a modification could be done ?
I have 2 of these 24 NVMe drives servers to test if needed.

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