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Re: [Qemu-devel] qemu dd sizes
From: |
Bartosz Fabianowski |
Subject: |
Re: [Qemu-devel] qemu dd sizes |
Date: |
Sun, 26 Sep 2004 00:27:57 +0200 |
User-agent: |
Mozilla Thunderbird 0.7.3 (X11/20040807) |
[This was sent to me off-list]
This was what I was looking for, however, I'm a little confused about
how to mount the file through the loopback device. Mount normally
requires a filesystem type as a parameter but if I create the "empy
image" with dd if=/dev/zero, there is no filesystem in the image. I
can't use newfs on the file until I mount it with the loopback
device..... How do I make the first mount ?
Quite simple really. First, create an empty disk image:
# dd bs=1 seek=4194303 count=1 if=/dev/zero of=image
1+0 records in
1+0 records out
1 bytes transferred in 0.000104 secs (9620 bytes/sec)
Then, create a loopback device:
# mdconfig -a -t vnode -f image
md0
Note the previous command told you what device name it created. Now, run
makefs on that device:
# newfs /dev/md0
/dev/md0: 4.0MB (8192 sectors) block size 16384, fragment size 2048
using 4 cylinder groups of 1.02MB, 65 blks, 192 inodes.
super-block backups (for fsck -b #) at:
160, 2240, 4320, 6400
Finally, you can mount the disk:
# mount /dev/md0 /mnt
As you can see, the file system is there, fully functional:
# df -H /mnt
Filesystem Size Used Avail Capacity Mounted on
/dev/md0 3.8M 4.1k 3.5M 0% /mnt
To clean up things, you'd first unmount the disk:
# umount /mnt
Then, you'd free the loopback device:
# mdconfig -d -u md0
That's all you need to do. Note however, that mdconfig is a FreeBSD 5.x
/ 6.x tool. If you're still on 4.x, you will need to use vnconfig
instead (it's not as intuitive, but quite easy to use).
- Bartosz