After spending considerable time thinking about this I've come to the
conclusion that on Linux systems we don't need Solaris style devid
support. Instead was can simply use udev if we are careful, there
are even some advantages.
The Solaris style devid's are designed to provide a mechanism by which
a device can be opened reliably regardless of it's location in the system.
This is exactly what udev provides us on Linux, a flexible mechanism for
consistently identifing the same devices regardless of probing order.
We just need to be careful to always open the device by the path provided
at creation time, this path must be stored in ZPOOL_CONFIG_PATH. This
in fact has certain advantages.
For example, if in your system you always want the zpool to be able to
locate the disk regardless of physical location you can create the pool
using /dev/disk/by-id/. This is perhaps what you'ld want on a desktop
system where the exact location is not that important. It's more
critical that all the disks can be found.
However, in an enterprise setup there's a good chace that the physical
location of each drive is important. You have like set things up such
that your raid groups span multiple hosts adapters, such that you can
lose an adapter without downtime. In this case you would want to use
the /dev/disk/by-path/ path to ensure the path information is preserved
and you always open the disks at the right physical locations. This
would ensure your system never gets accidently misconfigured and still
just works because the zpool was still able to locate the disk.
Finally, if you want to get really fancy you can always create your
own udev rules. This way you could implement whatever lookup sceme
you wanted in user space for your drives. This would include nice
cosmetic things like being able to control the device names in tools
like zpool status, since the name as just based of the device names.
I've yet to come up with a good reason to implement devid support on
Linux since we have udev. But I've still just commented it out for now
because somebody might come up with a really good I forgot.
5be28776fb