BSD Partition pg4

Please keep your hands and arms inside the vehicle until it has come to a complete stop.
Now I need to do a reboot. At the command prompt:

# shutdown -r +3

shutdown, do I really need to define this.
-r reboot
+3 initiate the command in 3 minutes
I rebooted no problem
Now for the scary math part.

# disklabel -r ad0

disklabel is same thing as the disklabel editor we saw in Fig.8. However we are doing it from the command line so as to make more
options available.

-r     read only
ad0    the first hard drive

 # disklabel -r ad0
 # /dev/ad0c:
 type: ESDI
 disk: ad0s1
 label:
 flags:
 bytes/sector: 512
 sectors/track: 63
 tracks/cylinder: 128
 sectors/cylinder: 8064
 cylinders: 784
 sectors/unit: 6330177
 rpm: 3600
interleave: 1
trackskew: 0
 cylinderskew: 0
 headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
 drivedata: 0
 8 partitions:
 #        size   offset    fstype   [fsize bsize bps/cpg]
  a:   204800        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 25*)               
  b:   138768   204800      swap                        # (Cyl.   25*- 42*)
  c:  6330177        0    unused        0     0         # (Cyl.    0 - 784*)
  e:    40960   343568    4.2BSD     1024  8192    16   # (Cyl.   42*- 47*)
  f:  5945649   384528    4.2BSD     1024  8192    16   # (Cyl.   47*- 784*)

Based upon the above information I was able to come up with the following chart.

kilobyte = 1024 bytes (1024 = 2^10), abbreviated KB (Kb is kilobits)

megabyte = 1024 KB = 1,048,576 bytes, abbreviated MB (Mb is megabits)

gigabyte = 1024 MB = 1,073,741,824 bytes, abbreviated GB (Gb is gigabits)

512 byte = 1 sector
1024bytes = 2 sectors
8064 sectors = 1 cylinder


bytes	       kilo	    mega	 giga	   sectors	       cylinders
512                                               1
1024	           1			                  2
1048576	        1024	   1	               2048
4128768	        4000	   4	               8064	             1
1073741824   1000000	1024	   1	    2097152	            261
2147483648   2000000	2000	   2	    4194304	            521
3221225472   3000000	3000	   3	    6291456	            781
4294967296   4000000	4000	   4	    8388608	           1041
6442450944   6000000	6000	   6	   12582912            1561
NOTE: this chart only applies to the hard drive shown . Other hard drives will have different
 sector/cylinder ratios.


Okay According to the chart I have a slight larger than 3 gig drive. Actually I have a 3.2gig drive 
so that is on the money.

Okay right about now you brain is about to explode and you are looking at that going "say what?".Lets take it a little easy and I will show
you how I did this. Lets look at some of the items that showed up in our result to the disklabel command.
bytes/sector: 512 that is how many bites per sector. So what? This is like an ugly word problem so we need to hang
onto all the information.
sectors/track: 63 You can ignore this
tracks/cylinder: 128 You can ignore this
sectors/cylinder: 8064 You can ignore this since what I am doing won't be to complicated.In other cases this will be very important.
cylinders 784 This is the total of cylinders and is also important.
So how is any of this important. The section under 8 partitions that is labeled a,b,c,d,e,f? The column marked size shows how many sectors are
being used for directories. Go to here to see how they coordinate if you are still confused.
a, is the / directory
b, is the swap directory
c, shows the whole drive
e, is the /var directory
f, is the /usr directory
We moved the /usr to ad1 earlier and this disklabel was only for ad0. So we no longer need the f section for the /usr on this drive. So we
need it's numbers.

       e   +     f   = new directory size for /var
     40960 + 5945649 = 5986609
    sector + sector  = new sector size
    That will also combine the cylinders when we increase the size of the partition.
       e   +     f   = new cylinder grouping
     42/47 +  47/784 = 42/784

Now get rid of the f section of ad0.

# disklabel -e -r /dev/ad0s1
# /dev/ad0s1:
type: ESDI
disk: ad0s1
label:
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 128
sectors/cylinder: 8064
cylinders: 784
sectors/unit: 6330177
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:   204800        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 25*)
  b:   138768   204800      swap                        # (Cyl.   25*- 42*)
  c:  6330177        0    unused        0     0         # (Cyl.    0 - 784*)
  e:    40960   343568    4.2BSD     1024  8192    16   # (Cyl.   42*- 47*)
  f:  5945649   384528    4.2BSD     1024  8192    16   # (Cyl.   47*- 784*)
  
~
~
~
~
~
~
~
~
~
~
~
~
~
~

I am in a vi editor now. The rules are very different here.So if you think you made a mistake. Hit ESC then : then q and then !.
:q! then press enter
That takes you out without making any changes. I go back in by disklabel -e -r /dev/ad0s1. Now lets see what I did. I moved the cursor
down to line f. Then I pressed dd. that is the d key twice. It should erase line f. I did that and now I want to save the changes. Press ESC
then: then w, then q.
:wq then press enter
This will save the changes I made.
Now do it again:

# disklabel -e -r /dev/ad0s1

# /dev/ad0s1:
type: ESDI
disk: ad0s1
label:
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 128
sectors/cylinder: 8064
cylinders: 784
sectors/unit: 6330177
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:   204800        0    4.2BSD     1024  8192    16   # (Cyl.    0 - 25*)
  b:   138768   204800      swap                        # (Cyl.   25*- 42*)
  c:  6330177        0    unused        0     0         # (Cyl.    0 - 784*)
  e:    40960   343568    4.2BSD     1024  8192    16   # (Cyl.   42*- 47*)
 
  
~
~
~
~
~
~
~
~
~
~
~
~
~
~

I need to change the size of e. Press ESC , :%s/40960/5986609/, then do the :wq again. the :%s tells the vi editor to replace the number
sequence 40960 with 5986609. Which is the number we came up with when we added the sectors. You can check to see if it
worked by disklabel -e -r /dev/ad0s1. The section under e should look like this:

e:  5986609   343568    4.2BSD     1024  8192    16   # (Cyl.   42*- 784*)

The size number went from 40960 to 5986609. See how the Cyl. numbers changed. Neat. Don't forget to exit in this case with :q!
Thought this was tough, it gets worse.

Back

Home

Next Page Using growfs