how to assure that a certain device (e.g. /dev/pass1) always is /dev/pass1 on subsequent reboots?

Raimund Sacherer rs at
Thu Sep 3 07:29:04 UTC 2015


> You probably don't need to worry about this: for permanently wired
> peripherals, the device names will generally be stable across reboots.

> For something like an autochanger -- given they're always plugged into
> the system and you can assume they're powered on -- then the devices
> will be numbered in the order the kernel probes for them at boot.

Just for your Info, I have one LTO5 Drive and one LTO6 Autochanger, both connected externally via pcix LSI SAS controllers. After Installation of the 2nd card (for the LTO6 Autochanger), upon reboot my devices where:

pass16, sa0, LTO5 drive
pass17, sa1, LTO6 drive
pass18, ch0, Autochanger

Yesterday I had to reboot the server and after reboot I got:

pass13, sa0, LTO6 drive
pass14, ch0, Autochanger
pass18, sa1, LTO5 drive

No hardware was touched since the installation, so there is definitly some sort of boot reordering going on. Maybe it is with the mps driver.

I added the device hints so at least I think until I change the physical hardware configuration I will get the same device names. I tried it yesterday with another reboot and they stayed the same.

It took me a while to figure out which driver runs the SAS controllers though, camcontrol devlist does not reference it, and I did not find it in pciconf either, but then I went trough the boot messages and found it very clearly stated. I just got confused because lspci in linux tells you the kernel driver the device is using, but the freebsd counterparts do not. Or maybe they don't show it the driver is compiled in.

Well, still lot's of learning to do, thank you for your info,

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