New Computer System

Jerry McAllister jerrymc at
Thu Feb 23 19:48:27 PST 2006

> 	I bought a new system (it was on sale), it has  180 Gigabytes
> of hard drive.  Naturally I want to slice it up, so where can I find
> the documentation on the slice/partition process and table.  As I
> recall, I can make 4 hard slices/partitions and then I can further
> break-down 1 (or more of them) to have logical slices/partitions.
> Where can I find documentation on the logical slices/partitions and
> how to use them?  Can I boot into a ( FreeBSD ) logical slice, and
> if so, how do I do it?  (For the 4 hard slices, one uses function
> keys  F1  thru  F4 .)  Has someone already setup the capability of
> booting into logical slices, and if so, where can I get it and its
> documentation?

It is all documented in the FreeBSD Handbook that is available online
at the web site.  

Forget the concept of logical slices in FreeBSD.   Everything is logical
actually, but not in the sense people are used to seeing in Microsloth.

Yes, you can make up to 4 primary slices on a disk drive.  That is also
true in MS world and others.    After that it gets a little different.

First of all, if you intend to only run FreeBSD on that machine or even
just that disk, then there is no reason to use more than one primary 
slice that you make the size of the whole disk (minus the scrap that
gets wasted in rounding to even cylinders for building slices and partitions)

Each slice can then be subdivided in up to 8 partitions a-h, but for
practical purposes partition c is reserved.  Many people also still skip
partition d for obscure historical purposes that no longer are meaningful.
Also, the b partition is usually used to designate space used for swap.

The only reason you need to divide the boot slice in to partitions
is for ease of management.   You will probably want a fairly small
root partition and a sizeable chunk dedicated to swap.   There are
two main reasons for using more divisions, but it depends on your 
usage and needs.

One reason is to make backups and restores manageable.  The bigger
the partition, the longer it takes to back up and to recover if there
is a problem.

The other reason is to help contain runaway disk usage and sometimes
to isolate one clump of users or applications from another clump of
users or applications.

For those reasons, I generally make the following partitions.

partition  Mount     size      comments
  a     =  / (root)  128MB
  b     =  swap      1.5 GB or more - 2.5 X the system memory.
  c     =  reserved  whole slice for internal use
  e     =  /tmp      512 MB   Occasionally something can fill /tmp and I
                              don't want it overfilling some other partition.
  f     =  /usr      2.5 GB   ports and a lot of stuff live there
  g     =  /var      1.5 GB   more if I want a database living there
                              also log files live there and can grow
  h     =  /home     All of the remainder of the whole slice/disk  
                              Pick any name. /home is easy to remember
                              I also move some directories such as /usr/local 
                              and /var/spool and /var/log and even /var/db/... 
                              in to the /home partition and make sym links
                              if they start growing..

If you have a second hard disk then you might want to make one large slice
and two partitions on it.   One for additional swap and the rest in to
extra space to use however you see fit.   I typically mount mine
as /work.


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