[linux-lvm] LVM and devices
mauelsha at ez-darmstadt.telekom.de
Sat Aug 28 18:33:28 UTC 1999
> Heinz writes:
> > > I may be a day late and a dollar short here, but I experienced a problem
> > > this morning when I added a new scsi drive to my 2.2.10 system. I know
> > > that the os scans for devices when the system boots and assigns device
> > > names then. Well this screwed up my volume groups because sda1 is now
> > > sdb1, you get the idea nothing new here. I know this has been discussed
> > > before.
> > Run vgscan and VGs should be o.k. again.
> Is it possible to integrate LVM with devfs in such a way that LVM actually
> creates the devices in devfs with proper names, like in AIX?
That's one of the future extensions.
> It should be
> able to identify PVs by UUID (if this is in 0.7,
Today it identifies PVs by PV number/VG name pair.
That obviously is not unique ;*)
But it's sufficient on a single computer system.
> I haven't had a chance to
> look yet). For that matter, LVM shouldn't be tied to the /dev names of
> anything, since you could just start traversing the available devices,
> find a list of UUIDs that make up a VG, and not have to worry about the
> /dev names of anything (nor even store them anywhere).
Actually, it depends on /dev namespace today.
But the sole reason for this is perforrmance.
We could simply throw that dependency away, if we go devfs or
could live with performance impacts without devfs.
> This would finally free us from the changes to device names that even long
> SCSI names in devfs can't handle. In AIX, you can move PVs around at will,
> or move disks for a VG from one system to another, and it will re-assemble
> itself, as it never uses the device names, except when showing user output.
If you do that in Linux (vgexport/vgimport), it works too but no UUIDs
with PVs and VGs today 8*(
Systemmanagement CS-TS T-Nova
Heinz Mauelshagen Otto-Roehm-Strasse 71c
Senior Systems Engineer Postfach 10 05 41
mge at ez-darmstadt.telekom.de Germany
+49 6151 886-425
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