DragonFly users List (threaded) for 2009-08
HOWTO - attach drives by serial number
The upcoming release will have automatic recognition of drive serial
numbers incorporated into DEVFS. Here is a quick how-to on how to
modify your boot and other files to recognize a drive by serial number.
In /boot/loader.conf you want to specify a kenv that tells the kernel
where the root filesystem is. You can specify a devfs-relative
serial number path instead of a drive name. Note that devtab labels
cannot be used in /boot/loader.conf as the boot loader does not parse
In /etc/fstab the device can be specified by serial number, but
that can result in long lines. It is easier to set up a label in
/etc/devtab and then reference the label in /etc/fstab.
So in /etc/devtab you could say:
fumach serno L41JYE0G
And then in /etc/fstab you could say:
# Device Mountpoint FStype Options Dump Pass#
fumach.s1d / hammer rw 1 1
fumach.s1b none swap sw 0 0
fumach.s1a /boot ufs rw 1 1
In /etc/rc.conf a dumpdev is typically set. This can simply be pointed
to the drive by serial number or by label. Example:
And that is it. If you've done it correctly you can move the drive
to almost any attachment, NATA, AHCI, SILI, firewire, whatever, and
the system won't care. USB is a bit more problematic as serial
numbers cannot usually be probed via USB attachments, which is why
we made USB start attaching at 'da8' (so it would be more deterministic)
instead of 'da0', but other then that the actual device the drive
attaches through (da0, da1, ad4, etc) becomes irrelevant.
I have booted up test boxes on multiple occassions without realizing
they had attached to NATA instead of AHCI because I hadn't set AHCI
mode in the BIOS. It's really quite nice when the attachment doesn't
care where the drive sits in the system.