benefit of GEOM labels for ZFS, was Hard drive device names... serial numbers

[Lawrence K. Chen, P.Eng.]

----- Original Message -----

> Al 01/03/2013 23:52, En/na Lawrence K. Chen, P.Eng. ha escrit:

> > I only have 15 drives...(12 HDDs and 3 SSDs) but the ordering of
> > drives seemed to randomize on every boot (wonder now if the
> > controller was doing some kind of staggering in spin ups.  And,
> > their other drivers cope with it.  They provide a v1.1 driver for
> > FreeBSD 7.2 or source to the v1.0 driver.)  And, then everything
> > moved around when I changed controllers a few times.
> 

> > I had resorted at one point to putting device.hints to force all
> > the
> > drives to keep their mapping.  Which caused problems elsewhere, and
> > a mess when I added another controller.  But, then I changed to
> > more
> > meaningful GPT labels and exported and re-imported my zpools with
> > '-d /dev/gpt', and now things are ok.
> 
> That reordering issue is what made me switch to geom labels first
> (IIRC I did by 5.x era) and next switched to GPT labels. The GPT
> allows me first to easily used those drives with ZFS and specially
> because those labels belong to the partition scheme and thus are
> filesystem independent.

> What I found specially useful is to be able to identify those drives.
> When I drive fails I know where it is because of the simple name
> convention I use; but having a blinking led helps a lot, specially
> when writing the recovery plan for the rest of the team.

> Gus

The GPT labels have come to be even more handy, because I had to switch out one (of two 5-bay) enclosures for a cheaper Rosewill one, due to a failing powersupply. The Rosewill one doesn't have LEDs. 

L