*BSD News Article 15767


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Newsgroups: comp.os.386bsd.questions
Subject: Re: New DISK! Newer Than disktab!!! OH SHIT!!! HELLLP!!!
Message-ID: <haley.736760098@husc.harvard.edu>
From: haley@scws5.harvard.edu (Elizabeth Haley)
Date: 7 May 93 07:34:58 GMT
References: <haley.736682158@husc.harvard.edu> <1sbactINN2tt@hrd769.brooks.af.mil>
Keywords: New Newer Newest Maxtor 7245AT
Nntp-Posting-Host: scws5.harvard.edu
Lines: 120

burgess@hrd769.brooks.af.mil (Dave Burgess) writes:
>OK.  Here goes.

>1.  This is covered in the FAQ.

Actually it is skimmed over in the FAQ... I kind of meant 
"Disk Partitioning for the Compleat Idiot"

>2.  The a: partition is the primary partition.
>    The b: partition is the swap partition.
>    The c: partition is the amount of the disk used by 386bsd (swap and data)
>    The d: partition is the entire disk.

This is for a second disk... Which may or may not include swap...
(mine does, cause I wanted too...)  I also wanted more than one
partition.

>3.  There are utilities that expect this map.  

Really? Why? (Unless it's data recovery things, but anything else
should read the label and proceed from there...)

>4.  All numbers in the map are in 512 byte blocks.
>400 Cyls for DOS, the rest of the disk for 386BSD.

DOS SUCKS!!! :-) (Never been on this machine, not even to rawrite the
TinyBSD and Fixit... I used an already Tainted machine... :-) )

>a: Cyls 400-901 (/usr)
>b: Cyls 902-965 (swap)
>c: Cyls 400-965 (entire disk used by 386bsd)
>d: Cyls   0-965 (entire disk)

Yeah, but I didn't find that out until I looked at the disklabel
created by the install... And even then there is a 40 cylinder dead
space between the end of user space and the start of swap...

Why is that?

Anyway, here is my map:

(Chris D. Take note...)

# /dev/rwd1d:
type: ESDI
disk: maxtor7245
label: 
flags:
bytes/sector: 512
sectors/track: 31
tracks/cylinder: 16
sectors/cylinder: 496
cylinders: 967
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# milliseconds
track-to-track seek: 0	# milliseconds
drivedata: 0 

5 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:   198400        0    4.2BSD      512  4096    16 	# (Cyl.    0 - 399)
  b:    31744   447392      swap                    	# (Cyl.  902 - 965)
  c:   479136        0    unused        0     0       	# (Cyl.    0 - 965)
  d:   479136        0    unused        0     0       	# (Cyl.    0 - 965)
  e:   248992   198400    4.2BSD      512  4096    16   # (Cyl.  400 - 901)

Some things I discovered  (for all you in novice land like me...)

1. As you can see this disk has 967 cylinders, but I only refer to 966
of them, 0 - 965... This is because it's good practice to leave the
"Landing Zone" cylinder out of it... This is usually the last
cylinder, and it's where the read/write heads hang out when your disk
is off...

2. a: can be a regular partition, b: should be swap, c: everything
386bsd will get to use, including swap. d: is the entire disk from 0 -
(cylinder_per_disk - 2)   [leaving out the Landing Zone]
You can then use e - h for your other partitions. I am not sure
whether you could specify b: as other than a swap partition and not
run into trouble, but you could surely make it a zero sized one
starting and stopping on the Landing Zone...

3. Stupid human trick: Don't forget that 400 - 900 refers to 501
cylinders. I did, for a while. No great problem I suspect, but
why waste a cylinder...

4. newfs'ing really is that simple if you have the label right:
newfs /dev/rwd?x where the question mark is the physical disk and the
x is a partition letter. Read the man page to be sure...

5. Write down the alternate super block numbers, at least a few of
them...

6. then fsck the partition: 
fsck -b <any alternate super block number> /dev/rwd?x 

Don't forget that fsck should be run on the RAW device.

7. As long as it checks out, you can then mount it and do disk things
with it...

8. Add it to the fstab... (follow the man page). Don't forget that
your new swap partition won't work if your kernel isn't configured for
it, but it won't cause you any problem to have it there. 

There's a cheeso capsule summary for us novice admins, except for one
thing: Whats the best way to determine the values for "fsize",
"bsize", and "cpg", and what the hell is "cpg"?

TSgt Dave: If you would like me to clean this up and what not for FAQ
inclusion, drop me a line via "reply"
--
Jesus saves sinners...
/****************************************************************************\
==============David Charles Todd, tHE mAN wITH tHREE fIRST nAMES==============
I/O Error: core dumped.
\*************************hacksaw@headcheese.daa.uc.edu**********************/