[cs615asa] HW3 dd restore hangs

[Rob Hoffmann]

I'm having some trouble with restoring from a remote volume using dd. I 
attach the ebs volume as /dev/sdf and then tar and dd the archive over 
with obs=256k. That works okay, but when I try to restore the files back 
using dd ibs=256k and piping it into tar, I see my all my files printed 
via -v flag but at the end of the listing the process just hangs and 
never finishes until I kill it.

Example output:

rob at heavy:~/programs/misc/sh$ tar cvf - . | ssh -i 
/home/rob/id_rsa-gsg-keypair 
root at ec2-107-21-185-218.compute-1.amazonaws.com 'dd of=/dev/sdf obs=256k'
./
./ec2-backup
./test/
./ec2-start-instance
40+0 records in
0+1 records out
20480 bytes (20 kB) copied, 0.067686 s, 303 kB/s
rob at heavy:~/programs/misc/sh$ ssh 
root at ec2-107-21-185-218.compute-1.amazonaws.com -i 
/home/rob/id_rsa-gsg-keypair 'dd if=/dev/sdf ibs=256k' | tar tvf -
drwxr-xr-x rob/rob           0 2012-03-16 13:45 ./
-rw-r--r-- rob/rob        6462 2012-03-16 13:40 ./ec2-backup
drwxr-xr-x rob/rob           0 2012-03-16 13:45 ./test/
-rwxr-xr-x rob/rob        1198 2012-03-15 18:50 ./ec2-start-instance
^Crob at heavy:~/programs/misc/sh$

The files are there and will transfer over if I use -x flag on tar, but 
dd will not end until I hit ctrl+C. If I remove the pipe to tar in the 
second command the content of the files will print to screen but it will 
still hang, so I know dd is the issue, not tar.

If I use of=/dev/st0 (SCSI tape device) instead of sdf that will backup 
& restore fine, but I can't mount the ebs volume under that name. Has 
anyone else had this problem?

-Rob