[Xen-users] Xen 3.0/FreeBSD Image Resize and 6.1 Status

[Andrew <andrew@xxxxxxxxxxxx>]

Hi,

I am currently using the FreeBSD 7 kernel/mdroot from 
http://www.fsmware.com/xenofreebsd/.  It seems to be working pretty well 
with some limited testing, but the website says that FreeBSD 6.1, 
released soon, should have dom0 and domU support.  Unfortunately, the 
last update was in February and it looks like the development has slowed 
down.
Has anybody heard any updates on this within the last month or 2?  I am 
really looking forward to running a known stable FreeBSD in DomU, and if 
dom0 support really works, I'll be in heaven.
Also, in the archive, I noticed a post in February asking about how to 
resize the mdroot that can be downloaded from the URL above but I'm not 
positive how to reply to that since I just signed up for this mailing 
list today.  Anyway, this is how I did it:
1. Use the dd command to create a new image with the appropriate size, 
something like:
 dd if=/dev/zero of=/path/to/my_big_img bs=1024k count=1000

bs=1024k means 1 megabyte, and count=1000 repeats 1000 times, making it 
1 gigabyte.  You can increase 1000 to 10000 for 10gigs, or whatever size 
you want.
2. Modify the xmfreebsd config file so there are two drives instead of one:
 disk = [ 'file:/path/to/mdroot,hda1,w', 
'file:/path/to/my_big_img,hda2,w' ]
** The next commands are executed inside of the domU, not in dom0! **
3. Boot the FreeBSD config and you will have two block devices, then 
make the new block a valid file system and mount it with:
 newfs /dev/xbd770
 mount /dev/xbd770 /mnt

Note that you should be sure you're not nuking your valid block device 
-- and please make a backup first so you don't have to download the 
image again if something breaks ;)
If you used the disk config from step 2 above, these two commands 
should work perfectly.  You can then run a df -h to see how much space 
is available in your image (should be a bit less than the size you 
specified).
4. Copy the data over to the new image.  There may be a better way, but 
here is the command I used:
 cd /
 tar cpf - `ls | grep -v mnt` | (cd /mnt && tar xpvf -)

The tar command does a copy preserving all the info and copies 
everything from / that doesn't match mnt (that way it doesn't start 
copying what it started copying).
The command after the pipe tells it to cd to the mount directory and 
eXtract (preserving fs info) in to the current directory.  Note that I 
used -v so it tells me each file as it's extracting.  You can take off 
the v for improved copy time, and even add an & to the end so you can 
mess around until it's done (for example, df -h occasionally to see the 
progress).
5. shut down your domU and modify the "disk = ..." config line to just 
use your new, bigger image.  Now it should boot in to the new image.
The only problem I've noticed with FreeBSD as a domU is an occasional 
error during boot up, at which point I have to destroy the guest and 
recreate it.  Seems like some sort of race condition, although it may be 
related to copying the root fs data the way I did but that seems 
unlikely.  Hope this is helpful to someone and I hope more operating 
system support is added to Xen soon.
- Andrew

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