I finally get the hype about rsync

[aysiu]

I've been backing up data for years now.

When I was in Windows, I did it by burning CDs... lots of CDs.

Finally, my wife and I invested in an external hard drive--what a life saver. I could back up 30 or 40 GB of data without having to burn 50 CDs. How did I back stuff up? Copy and paste. Sure, it took a long time, but that seemed fine.

Later, after moving on to Ubuntu, I still did the copy and paste for quite a while.

I toyed with a few GUI programs for backing up, but they always seemed convoluted to me, for some reason.

Then, I tried just .tarring my files with a script that I saved to /usr/local/bin and called backupfiles. I liked the script. It was fun, but it still took a hell of a lot of time to copy all those files.

Finally, I read an article about rsync. I'd read numerous times on these forums that rsync was great... usually accompanied by vague instructions like

Try rsync

I have to say I really despise the acronym RTFM (read the f'in manual)--not so much because of its rudeness but because of its presumptuousness and false assumptions... namely that reading the manual actually helps new users.

I did

man rsync

and my eyes glazed over. "Yeah... so..? How do I use it?" The article in the news explained it all quite nicely, even to a semi-beginner like me.

So I used rsync with the -av options:

rsync -av /old/directory /backup/directory

and it took quite a while, but when I did it again, only my Firefox profile (which I had modified slightly since) was backed up.

The beauty of rsync is its being a single command that does not require root privileges, preserves links, and does differential/incremental backups. I was so won over by rsync that I even converted my wife over to it to use on her Mac Powerbook.

One thing that I found out the hard way, though--don't use rsync on FAT32. It's got to be Ext3 or HFS+.

[Iandefor]

That actually sounds useful. My only question: it synchronizes changes in directory contents, sure, but what about file contents? Does it check for file consistency as well?

[aysiu]

Well, as I understand it--and obviously there rsync experts out there who may know better--it compares modification dates and file names (and possibly file sizes?) and then copies over the file if it's been changed since...

... so, theoretically, if the file contents have been changed, so has the modification date, right?

[Iandefor]

Well, as I understand it--and obviously there rsync experts out there who may know better--it compares modification dates and file names (and possibly file sizes?) and then copies over the file if it's been changed since...

... so, theoretically, if the file contents have been changed, so has the modification date, right?

Yup. I didn't see that if it was in the article.

[aysiu]

No, that may not be in the article, but rsync appears to copy files that have been modified, so I'm assuming it goes by modification date, as grep-ing the contents of each file and comparing the two would take forever.

[prizrak]

I guess the real question would be, does it check whether the synching was successful.

[prizrak]

No, that may not be in the article, but rsync appears to copy files that have been modified, so I'm assuming it goes by modification date, as grep-ing the contents of each file and comparing the two would take forever.

And not always possible.

[aysiu]

I guess the real question would be, does it check whether the synching was successful.

I'm not sure what you mean--whether the files actually copied... or just put empty placeholders?

[Iandefor]

I'm not sure what you mean--whether the files actually copied... or just put empty placeholders?

I think he means checking if the transfer actually copied the files bit-for-bit successfully. Sort of like how you should check the md5 checksum of iso's you download.

[Polygon]

That actually sounds useful. My only question: it synchronizes changes in directory contents, sure, but what about file contents? Does it check for file consistency as well?

thats what i was thinking as well, like if you have a text file named "thingstodo" and you have like "wash the dishes". then you use rsync and that file gets backed up to some directory. But if you add more to that text file, like "take out the trash", will rsync know that the file was edited and backup and overwrite the previous file that got backed up, or will it not back up the newly edited file at all because it already exists in the backup directory?

otherwise, this looks like a useful program. i will have to check this out.

and why didnt you use dvds before you discovered rsync... you could of backed up a lot more for a lot less that way, but external drives i agree are the best solution