Why are backing-up programs so often poorly-written?
 

Hi guys,

I have used many different disk backup programs over the years, both free and proprietory, yet very few indeed seem able to reliably deliver the goods on every PC I've had. The problems they've given me are too many and varied to list here, but looking on the relevant message boards, I see very many others have had the same problems as I have.

So what is it precisely that is SO difficult about writing a stable and reliable backup program? I mean, how hard can it be to simply copy a stream of bits from one hard drive to another?? There must be some issues here I'm not aware of, because on the face of it, this simple process SHOULD be a cakewalk. Any ideas?

CC.

I am not aware of what specific issues you are talking about, as I can't say that I have ever used any backup software that had such glaring issues. Though personally I rely on my own scripts for backups, so I haven't put as much time into existing software as I imagine most others would have.

My logic professor would say that you are "begging the question."

As in: "have you stopped beating your wife?"

Ever tried a program called 'dd' ? The only way it can fail you is if you put in the wrong output device.

Naturally I have. But it's so crude, slow and inefficient. Then later when you need to write the saved data back to restore a partition, it refuses on the ground that the target partition is smaller than the source (when it HAD to be that way for it to work in the FIRST place)!

If all you want is fault tolerance then mirror (RAID-1) the hard disk. What happens when a user overwrites good data with bad data though? Both disks will contain the bad data. That's when you need a real backup. Unfortunately many people realize this too late.

If dd is inefficient then you're not using it right.

See:
http://www.linuxquestions.org/questi...ommand-362506/

If you don't set the 'bs' option, that's what may make it slow.

Back-up 'programs' are usually written for the lowest common-denominator (Windows and Ubuntu users).

I have written several backup scripts and they are EXCEEDINGLY easy to write, are simple and work well.

It's so easy to tar/gzip the /home directory and ftp it to a backup server. Use cron to fire it off and/or let the user manually execute it (for laptops usually).


Even Windoz backup scripts are easy-
I write a batch file that invokes 7-zip to back up the desired directories and files then save it to a backup media (using SMB if the media is a back-up server). Invoke the batch file with the SCHEDULED TASKS or give the user a shortcut so they can execute the back up (again for laptop users).


EASY!

Amanda is quite easy to use. There are many others.

Windows Backup is a very well-featured program.

So is OS/X's Time Machine.

Acronis makes a good commercial backup program too, both Windows and linux. Personally, I like rsync.

Backup programs suck because you haven't written one yet!

Seriously, it seems like a simple problem but think about how hard it is. I need to back up my email. Do I copy messages individually or all together. If individual, it's fast but takes up space; if in bulk then it's more space-efficient but I have to make a new archive every time. I want to back up music / video. There's no point in compressing because they're already compressed; doing so again would be a waste of time usually. Oh but what if I edited the tag info in a ton of songs, do I send them all or try to find the parts of the file that changed? Now do I backup to disk, over the network, somewhere in the "clouds"? Do I do it automatically or at a certain time? Do I let the hardware do it (RAID), the OS do it (filesystem hooks), maybe cron or make it manual?

Maybe, like many things, there is no one-size-fits-all solution. Just like all the other joke arguments of Emacs vs. Vi or C++ vs. Java or insert-your-own-computer-religious-war-question-here. You have to think about what you want, narrow down your choices to the things that even make sense for you first, and if you then find after thorough research that all the appropriate solutions suck, do it yourself or ask someone to do it for you. Not with vague generalities, but with actual requirements.

Acronis sucks. It's widely regarded as "very buggy" (well, the TI series, anyway). I still have to use it sometimes, but only if all else fails. Yesterday, it took NINE HOURS to restore a 17Gb backup image on my old Dell Pentium 4. One of those hours was wasted just in detecting the USB drives! I was just relieved it finished the job without errors (even though I had to get up at 5am to turn the computer off).

Yes, well what you're describing *is* easy. But I only ever want to do *full* system+data backups (image the entire used partition) so I reduce my computer to a single file. Very few proprietory backup programs seem capable of reliably doing this across a range of fairly standard hardware.

That could be the problem there. What you are trying to do really isn't a very good idea. Trying to backup a running system into a drive image is definitely not the way you want to be doing system backups.

I don't recall saying that! As a matter of fact, it's something I never do and always boot from a live CD to control the process. However, I have tried out a new backup program from Terabye which somehow locks a running system so you can carry on working whist the backup is made. It works, too!