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Re: starting Fedora Server SIG



Matej Cepl wrote:
On 2008-11-20, 07:00 GMT, Les Mikesell wrote:
Maybe - but it isn't a real solution. You still have to deal with identifying the device before and during the labeling process. If you can do that, you didn't really need the label.

Sorry, maybe I don't understand, but what's so difficult on the following?

tune2fs -l /dev/sda1 |awk '/UUID/ {print $3}'


The disk may be unformatted at this point and not have a UUID. Or if it has filesystems, they may be types that don't support labels or UUID's (vfat, etc.). But the point is that if you already knew it was /dev/sda1, why do you need to care about anything else?

There are at least two different use cases here. One is that you have a single machine where you move a known small set of drives around to different positions (or they are usb/firewire, etc. where you don't have a concept of position) and you always want the same partition mounted in the same place regardless of where it ends up in the physical order. I do have a machine like that and understand why the concept of labels or uuids is useful - but in that case I made all of the partitions into raid1 md devices (some mirrored, some with the 2nd member specified as 'missing' which accomplishes the same thing and lets me plug in a disk with a matching partition and make a backup by adding it to the raid.

The other use case is where you have a large number of servers with swappable drives and regularly swap them around. Scsi/sca backplanes are usually predictable as to drive ordering so if you physically insert a disk you automatically know the /dev/sd? name for it. This may not be true for newer sas/sata controllers with raid logic that hides the physical drives behind 'volumes' even if you configure one drive per volume, though. But in any case you need a way to discover and identify devices before and during the partitioning and filesystem creation steps, and labels can't help you then.

--
  Les Mikesell
   lesmikesell gmail com


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