nested labels

[Adam Martin]

On 2006 Sep 28 , at 01:08, Jeffrey Katz wrote:

> Adam Martin's discussion of nested partitions was very enlightening 
> and useful.  A nice thing about the approach is that it can be used on 
> a "dangerously dedicated" hard drive.

	Well, it merely takes advantage of GEOM.  You can even nest GPTs, and 
other things inside of BSD labels, and vice versa.  The most important 
thing to keep in mind is that every time that you create a new "device" 
from partitioning a device, GEOM allows you to install partitioning 
tables on them, and make more "devices" from those.  As can be seen 
from my absurd case.

	That said, there are many good reasons to avoid over-partitioning a 
drive.  Data can become more difficult to organize, as various 
filesystems have limited space, and start filling up at different 
rates.  Also, failures in the sectors that contain the partitioning 
tables will cause you to have great difficulty in reconstructing data, 
in the event of disc failures.  Don't over abuse nested partitions.  I 
like to keep a paper copy of the actual sizes of all the entities in my 
partition tables, and their offsets, and mountpoints.  At least once, 
this knowledge has helped me recover from serious disc failure.

	With the advent of half-terabyte, and larger drives, we're nearing the 
upper bounds of 32-bit bounded filesystems, and partitioning tables.  
GPTs are supposedly able to handle larger volumes than 2TB.  Keep an 
eye on the freebsd large disc project:  
http://www.freebsd.org/projects/bigdisk/index.html

Cheers,

--
Adam David Alan Martin