On Wed, 16 Jun 2010, Harry Palmer wrote:
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.
hi Harry,
i'm far from an expert but will share what i know.
Beginning my effort to encrypt a 300GB drive in a 64bit Ultrasparc,
I followed these initial steps:
i'm also into using 64bit Ultrasparc architecture.
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?)
think they are hard set (and necessary for certain recovery senarios).
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)
that looks fine. filled the whole "allocated" space in the a partition.
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
c is from unix tradition and represents the entire surface of the disk
in a single slice.
and:
# ls -l /home/cy
total 576661216
-rw-r--r-- 1 root wheel 295178420224 Jun 16 03:39 cryptfile
same as dd reported.
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.
slight misundertanding. df reports usage with an allowance for warning
before file system is exhausted, so the default capacity is 105% and
for proper operation, shouldn't be used beyond 100%. i believe that
as a user you can't fill it more than 100% (as reported by df) but root
can fill it beyond (necessary for some recovery senarios).
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.
think you did everything right and will feel right at home with OpenBSD
after you take into account the reserved 5% of filesystem capacity built
in to df.
-ron
