Originally Posted by wayne.liu
Thanks for the suggestions. I might give it a try later. At this point, I am really looking for a way to get tar working on removable hard disks as with tape drives (i.e. without having to explicitly specify the file size).
Are you trying to create a drive mirror (image backup) on a removable drive? Rsync is a far better backup solution for this than tar. (and dar doesn't make sense in this context... as I said, I don't quite know what you're trying to do.)
I rejected tar for myself and didn't recommend it to the readers in the how-to article I sold on Linux drive backups because it doesn't provide built-in error checking and it doesn't handle differential backups. The time to find out that something didn't go right with a file transfer is during, not when your primary hard drive is down for the count.
The only good reasons to learn the ins and outs of tar I can think of is if you are learning Linux because you want to be a sysadmin or if you're taking CS classes where the instructor expects you to learn it... the only way I use tar is when I'm decompressing a tarball for a build-from-source. However, my approach to my box need not be yours, of course, in my case, this is the only computer I've got and I do business with it... which makes me pretty conservative with respect to what I will and won't do with the workstation.
Rsync (for remote synchronization) is a far better solution for removable drive mirrors... it can be scripted to provide full image backup the first time around and differential backups afterwards as I set it up, you can set yours up to back up only the directories that interest you. The difference between a full image backup and differential is the difference between several hours and a few minutes when I do my every-other-day drive backup. And I can state from experience that a full restore done with an rsynced mirror works... when my HD failed a few months ago, I dropped in the mirror and had my computer back up within a few minutes.
If you are interested in trying this, you might check my rsync script which has been backing up my own system to a mirror drive for the last year or so in my how-to article on backups here:
I'm using Fedora Core and you probably aren't. Just modify the top level directories in the script to match whatever's in your distro except for /proc ... presumably, that shouldn't be backed up on your distro, either...
Sorry I couldn't give you what you asked for... but if what you really want is simply to back up your drive without extra hassle or concern about "are the files really there and not corrupt?", what's here is what I think you actually want.