Backuping up a Reiser4 partition with "dd"...

juanbobo · 03-18-2006, 02:40 PM

I have a 13GB Reiser4 partition that has only 4GB of data on it. I want to make an image of the partition with "dd", but I don't want to backup the empty space on the drive, how is this possible? Does a tree rebuild with fsck.reiser4 move all of the files to the beginning of the partition?

acid_kewpie · 03-19-2006, 07:07 AM

well you either want to back up all the files, OR you want to image the partition... i assume you mostly don't want to waste the space? just compress the dd output:

Code:

dd if=/dev/hdb1 | gzip -9 > /var/images/hdb1.gz

juanbobo · 03-19-2006, 05:39 PM

Yes, I was considering that, but I don't necessarily want the partition to be 13GB when restored.

JZL240I-U · 03-20-2006, 06:25 AM

@acid_kewpie Assuming it isn't the root partition of the file system wouldn't it be better to do

Code:

dd if=/dev/zero of=/file/on/partition/in/question bs=512
rm -f /file/on/partition/in/question

to optimize the ensuing compression?

acid_kewpie · 03-20-2006, 06:49 AM

i wouldn't have thought so... dd is IO intensive, gzip is cpu intensive. A such you can use both resources to get the job done in a single run wihtout much more time being taken. infact, it could even be quicker to do it this way as it will take less time to write the compressed image than the uncompressed one, so you may save time over all, and get the end result you want.

JZL240I-U · 03-20-2006, 06:54 AM

Yes, sounds plausible that it is quicker. I was thinking of the compression-rate. After all, gzip would compress all the garbage of his entire 9 GB unused space. If that is levelled to a huge zero

, shouldn't it compress that much more "tightly"?