Linux advice?

[desperance]

Okay, I have here on my desk an external hard drive big enough to copy my entire installation onto, rather than just backing up the data.

Questions, then:

1) Should I do this?

2) How do I do it?

3) Should I make it bootable, and if so, how?

4) What other questions should I be asking?

[En passant: it makes little buzzy-clicky noises, which are very quiet and discreet but none the less New Noises on the Desk, and I find myself very aware of them. That's probably a good thing. One should be aware of new toys, for at least a day or two. Hence all this how-can-I-use-it-best anxiety.]

Comments

[durham-rambler.livejournal.com]

I have recently bought a larger version of what you have (to be precise, a 750 Gb Seagate FreeAgent) which I use to back up shewhomust's and my disks. The answers to your questions are:

1. Yes.
2. We use Acronis TrueImage to back up our Windows systems. The current Amazon price is £29.99 and I am not sure if it will do all its tricks under Linux, though the way it recovers if you have completely lost your system is to boot Linux from a CD and then copy your backup to the new disks, which leads me to a suggestion:
   
   Why not boot a live distribution from CD and then mount both your PC hard disk and your external hard disk and then copy (a) to (b) -- or (b) to (a) if you are recovering? I'm not a Linux expert: can you mount the source disk read-only? That would be a good idea to avoid changes in mid-flight.
3. I think you could get away with a CD boot, as described above.
4. Do you want to do incremental or differential backups? These would save time and disk space but you would probably want a program to do them. Acronis does it in its Windows guise, I'm not sure about Linux.

[cherylmmorgan.livejournal.com]

1) Yes

2) Can't give you Linux specifics, but ask Charlie Stross.

3) Ideally. What Kevin and I do (and we got this from Charlie) is make drive clones. So the backup drive is *exactly* like the live system, and in the event of a disaster we can just swap one for the other. Of course we mainly use laptops, and swapping drives is very easy with them. I'm not sure what you have.

4) How do I placate Murphy?

[jeremy-m.livejournal.com]

1) In my day people did incremental backups rather than copying the whole installation, but now that disks are free in cost and infinite in size, there's no particular need to do backups efficiently - copy the whole installation every time if you like.

2 and 3) You can copy one disk to the other as blocks rather than files using dd, so you get everything, though probably best to make a partition the same size as the disk you're copying from as any extra space would be lost otherwise. That should make the new disk as bootable as the old one, though I'm not 100% sure how the BIOS bootstrap, the disk's master boot record, and the partition's boot record all interact when you dd things: if it doesn't work first time use grub to make a multi-boot master boot record that does what you want.

On the question about mounting read only, yes, there's a ro parameter to the mount command, when using manually or in the /etc/fstab file. More generally, Unix always has a way of doing anything you should be doing. And several things you shouldn't.

[jeremy-m.livejournal.com]

Except, that on thinking about this I notice it won't work in several ways.

If you put the copied installation into a partition it won't boot for lack of swap space, so you'd have to make a swap partition too, and tweak the copied installation to use it. More worsely, the two disks probably don't have the same name (e.g. /dev/sda2), so you'd have to tweak references to the disk name in the copy as well.

So by the time you've got the copy to be bootable, it won't be a copy, and wouldn't then work if you copied it back to the original. So not ideal as a backup really.

New plan: don't try to make it bootable, just make it a true backup copy.

E.g. boot from CD and use dd to block copy the old disk to the new one and put it in a drawer. When you need to restore, boot from CD and use dd to block copy it back. Don't do anything more complicated and then Nothing Can Go Wrong.

This will also copy and restore any Windows or DOS partitions and multi-boot support on the old disk as a side effect.

[desperance.livejournal.com]

Don't do anything more complicated and then Nothing Can Go Wrong.

Hee. Of course I believe this...

Thank you. I shall devote a little skull-sweat to the syntax of dd, and pursue this option.

[jeremy-m.livejournal.com]

Another scheme, perhaps more interesting for its paradoxical elegance than anything else, is to make the new disk a separate bootable unix and then backup each of them using dd piped through compress to a file. As that'll be quite a small file compared to the disk it's from, you could probably put the complete backup of each on to the other. Which feels like cheating the universe in some way and may spiral out of control if you do it more than once.

dd </olddisk | compress >/newdisk/filename.Z # tempting Providence

[alexmc.livejournal.com]

1) Dont know. I dont. But then I currently have approximately ten unix based systems in the house.

2) What specific Linux do you use? I think you should be able to find a tool that does this for you. I would investigate "gparted" which is useful for creating partitions and copying them. That may work for you. Take care. Backup everything first.http://gparted.sourceforge.net/

3) Well if it isnt bootable then that kind of destroys the point of copying everything over. Personally I try to keep the operating system separate from the data. If my computer dies I only restore the data - I would recreate the operating system from scratch - not backups.

4) Do you have a LiveCD - ie can you boot from a CD or DVD drive?
Your BIOS may or may not allow for booting off a USB device. Your external disk is USB, right?

[alexmc.livejournal.com]

Yes yes, I do see the irony in telling you to back up everything when you are trying to create a backup :-)