Quoting Harry Palmer <tumblew...@fast-mail.org>:
Hi there.
I'm fairly new to openbsd and I'm hoping someone with better
understanding than me of how its disk handling works can help.
Beginning my effort to encrypt a 300GB drive in a 64bit Ultrasparc,
I followed these initial steps:
1. used disklabel to create a single slice "a" on the drive
2. made a file system with newfs (is it necessary to have so many
backup superblocks?)
3. mounted sd2a on "/home/cy" and touched it with an empty file
"/home/cy/cryptfile"
4. zeroed out the file (and efectively the drive) with
"dd if=/dev/zero of=/home/cy/cryptfile bs=512"
Here's the (eventual!) output of (4):
/home/cy: write failed, file system is full
dd: /home/cy/cryptfile: No space left on device
576520353+0 records in
576520352+0 records out
295178420224 bytes transferred in 19810.722 secs (14899932 bytes/sec)
Now I have:
# disklabel sd2a
# /dev/rsd2a:
type: SCSI
disk: SCSI disk
label: MAW3300NC
flags: vendor
bytes/sector: 512
sectors/track: 930
tracks/cylinder: 8
sectors/cylinder: 7440
cylinders: 13217
total sectors: 585937500
rpm: 10025
interleave: 1
boundstart: 0
boundend: 585937500
drivedata: 0
16 partitions:
# size offset fstype [fsize bsize cpg]
a: 585937200 0 4.2BSD 2048 16384 1
c: 585937500 0 unused
and:
# ls -l /home/cy
total 576661216
-rw-r--r-- 1 root wheel 295178420224 Jun 16 03:39 cryptfile
and:
# df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/sd0a 1007M 44.8M 912M 5% /
/dev/sd0k 247G 2.0K 235G 0% /home
/dev/sd0d 3.9G 6.0K 3.7G 0% /tmp
/dev/sd0f 2.0G 559M 1.3G 29% /usr
/dev/sd0g 1007M 162M 795M 17% /usr/X11R6
/dev/sd0h 5.9G 212K 5.6G 0% /usr/local
/dev/sd0j 2.0G 2.0K 1.9G 0% /usr/obj
/dev/sd0i 2.0G 2.0K 1.9G 0% /usr/src
/dev/sd0e 7.9G 7.7M 7.5G 0% /var
/dev/sd2a 275G 275G -13.7G 105% /home/cy
I have no understanding of this. I've never seen a df output
that tells me I'm using 13GB more space than the drive is
capable of holding.
I ask here because there's obviously potential for me to lose
data somewhere down the line. I'll be grateful if anyone can
explain where I've gone wrong.
I've seen the greater than 100% full on a UFS? filesystem before when
you exceed the size of the filesystem. There is space in the
filesystem for "lost+found" and all those superblocks? you were
complaining about that can get overwritten if you write too much to a
partition.
So setting up your "dd" to actually stop before you overfill the
filesystem is what you need to do. (using bs=# count=# ... info you
can get before you start initializing your file with the df command
without the "-k or -h" to get number of blocks and block size)
I'm sure the fine people on these lists will correct me if I'm wrong
in my assumptions... :-)
George Morgan
