On 2006 Sep 23 , at 16:15, J65nko wrote:

On 9/21/06, Jeffrey Katz <[EMAIL PROTECTED]> wrote:
I have hit the limit of 8 disklabels per slice.  Supposedly, one can
create lables within a label, thus overcoming this limit.  I googled
everything but could only find references to gpt-- nothing about nested labels or partitions. Can anyone detail the steps involved in setting up
nested labels or partitions?

There was some previous discussion in this thread about the merits of multiple partitions, and why one would need so many. I will not delve into a long discussion on this; suffice it to say that there are many valid reasons to create more than 8 partitions on one disc, and that these reasons are usually unique to the site in question. If a system administrator feels that he needs more division of storage, he likely has a good reason.

A slice can have 8 labels, a disk can have 4 slices, so 4 x 8 labels =
32 labels
Deduct from those 32 the reserved "c" and possibly "b" and you still
have a lot to spare ;)

Although, the above, using PC partitions with nested BSD labels within, is a viable solution, and can be used safely with sysinstall, to give you a nice GUI (well, not gui, but menu at least) to work with the partitions; the biggest problem here, and the reason I stopped doing this, is that you have to know in advance how many meta-partitions you want, and what sizes they are. For example, my old 160 GB disc was divided into a 32 GB and a "remainder" PC partition. Those each had 7 major partitions therein. (You can use partitions a and b for filesystems. It's just convention that we use a and b for root and swap.) As this can be done safely, and straightforward from the sysinstall program, I won't go into details here.

What you can also do is use the bsdlabel(8) program on any slice. In FreeBSD, geom labels devices very simply, and sensibly. E.G.: /dev/ad0s1hs2def is a valid device name. Granted it is a very absurd case, but it illustrates how one can use it. In geom, any PC partitions are appended as "sN" where N is 1 thru 4 for primary partitions, and 5 thru (unknown?) for logical partitions. In the case of bsdlabel (disklabel) partitions, they receive letters a thru h. In the above example, the primary master disc's first primary partition has a bsdlabel, which the last partition of it has a PC partition table within, which has a primary partition in slot two. That nested PC partition has a BSD partition, with a partition in slot d, which has more BSD sub-labels. (Need I go on, with this pathological example?)

In summary, you can make bsdlabels, inside of a partition (PC or BSD). This is done by just running bsdlabel -w on the partition in which you wish to create the sub-partitions. (bsdlabel -w /dev/ad0s1h, for example) You can then create unlimited levels of partitions. Remember that after running bsdlabel -w, you must run bsdlabel -e, to edit the partition. Do not forget to create filesystems in the partitions (newfs -UO2 for UFS 2 with softupdates.) As far as conventions, I prefer to put the "extended" partition into slot a, and set its type to "unknown." In cases where slot a is taken by a root partition, I use slot h. I find that sticking to this convention helps keep me organized when employing this technique.


Adam David Alan Martin

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