New Driver for MegaRaid 6Gb/s and 12Gb/s Card

[Kevin Day]

On Apr 19, 2013, at 10:59 AM, Scott Long <scott4long at yahoo.com> wrote:
> 
> What will the exposed device names of the arrays be under the new driver?  Will it still be /dev/mfid* ?  If it's not, then this is where the problem lies.  Many users still use device names in their /etc/fstab for mounting all of their filesystems at boot.  If you have two drivers that will compete for the same hardware and give that hardware different names, they will break the fstab files for those users and they upgrade over time.  A similar situation occurred several years ago with the Intel e1000 driver; it was split into two drivers, with certain hardware that was supported by the old hardware going to the new driver.  That broke the network configuration for many users and caused years of pain and unhappiness as users upgraded and were hit by the switch.  We don't want that to happen here.
> 
> The real solution is that we need to have a single common naming convention for all disks (and for network interfaces), and leave the details of individual driver names out of the configuration part of the system.  That's not likely to happen any time soon.  The other solution is to mandate that users use volume labels for mounting their filesystems, but that's not likely to happen either, and even if it did, it present challenges for migrating existing users.  The only remaining solution that I can think of is to have the mfi and mrsas drivers share the same devclass for their disk interfaces (mfid*), but that's a hack that has not been fully explored in FreeBSD.  Still, I'd encourage you to try it and see if you can make it work.  If you have any problems, email me directly.

Some Linux distributions had a flag day where upgrading beyond a certain point caused a one-time popup asking if you wanted to convert /etc/fstab to volume labels instead of device names. You could say no and proceed normally, but if you said Yes it rewrote fstab to use labels. I'm not sure where we could hook this so it happened both with freebsd-update and source upgrades, but it would be nice to make it painless to switch.