[Novalug] LVM query
Jon LaBadie
novalugml@jgcomp.com
Mon Jul 19 17:32:35 EDT 2010
On Mon, Jul 19, 2010 at 09:25:44PM +0000, Jeff Stoner wrote:
> On Mon, 19 Jul 2010, Jon LaBadie wrote:
>
> >Of the 4, two are internal, the other pair external
> >drives connected by USB. I was planning on pooling
> >the internal pair and the external pair into two
> >volume groups. But then I thought, why not a single
> >large VG?
>
> /me runs away and hides
>
> >The reason I'm hesitant to do a single group is
> >the external USB drives stop spinning after a period
> >of inactivity. Then they are slow to reconnect.
> >Is that likely to cause problems with a single
> >large file system spanning the 4 drives when one
> >might not be available immediately?
>
> I, honestly, would not use USB drives in any kind of software RAID
> or LVM configuration. My mantra has always been "USB drives are TAS
> (temporary attached storage), use them to transport data between
> systems when you can't use the network or as independent backup
> units."
>
> You can try this if you want but one thing you may have to ensure is
> a consistent naming of the USB devices. Disk 1 may be /dev/sdh1 and
> disk 2 /dev/sdg1 one day but reboot and disk 1 may become /dev/sdg1
> and disk 2 /dev/sdh1 (flip-flop.) If you've built volumes using
> those device names, you may very well be screwed.
>
> Dambit...now I'm curious. I'll have to try this and see what happens.
>
In a previous incarnation, the same machine with the same USB drives
(plus part of one internal IDE drive) were used for backups. There
I assured consistant naming/mounting by using UUIDs in the fstab.
But I see your point with LVMs. What name will be used when creating
the pv's and adding them to the vg. That will have to be consistant,
but how?
jon
--
Jon H. LaBadie novalugml@jgcomp.com
JG Computing
12027 Creekbend Drive (703) 787-0884
Reston, VA 20194 (703) 787-0922 (fax)
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