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tsinghoi
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Joined: 28 Sep 2005
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 Posted: Thu Nov 29, 2007 9:15 pm Post subject: I want to back up my root partition, what switches do I use? |
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| I want to copy all the contents of my root partition (with gentoo on it, reiserfs) to another partition (reiserfs). Should I use the cp command? and what switches should I use? (whats the difference between -r and -R anyway?..) I want it to be a perfect working copy. |
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NeddySeagoon
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Joined: 05 Jul 2003
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| Posted: Thu Nov 29, 2007 9:23 pm Post subject: |
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tsinghoi,
Copying a live working root is always a problem. You are better to do it from a liveCD. should work that way.
You do not want to copy the content of /dev, /proc or /sys.
Think about /dev/ for a moment - you can read the entire content of your hard drives several times over by copying /dev.
Why do you want the copy ?
If its to add extra space, its easier to move something like /home or /usr to its own parition.
Keep in mind the image will only work if it ends up on another drive at the same partition number - /etc/fstab will be wrong otherwise.
Also if /boot is a directory on root, you may need to reinstall grub to the MBR, which is outside any filesystem
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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neiljw
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Joined: 12 Nov 2007
Posts: 166
Location: Telford, UK
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| Posted: Thu Nov 29, 2007 9:23 pm Post subject: Re: I want to back up my root partition, what switches do I |
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| tsinghoi wrote: | | Should I use the cp command? |
No -use dd (man dd).
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Be lucky,
Neil |
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tsinghoi
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Joined: 28 Sep 2005
Posts: 15
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| Posted: Thu Nov 29, 2007 9:49 pm Post subject: |
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| NeddySeagoon wrote: | tsinghoi,
Copying a live working root is always a problem. You are better to do it from a liveCD. should work that way.
You do not want to copy the content of /dev, /proc or /sys.
Think about /dev/ for a moment - you can read the entire content of your hard drives several times over by copying /dev.
Why do you want the copy ?
If its to add extra space, its easier to move something like /home or /usr to its own parition.
Keep in mind the image will only work if it ends up on another drive at the same partition number - /etc/fstab will be wrong otherwise.
Also if /boot is a directory on root, you may need to reinstall grub to the MBR, which is outside any filesystem |
My partition table has become so screwed up (and at this point seems unrepairable). I tried repairing it and its definately not what it originally looked like. All 7 partitions housing 4 OS's (vista, xp, osx86, gentoo) are mountable and I can see files (off a livecd), but I cant boot to any of the OS's from grub! And I dont know enough about computers to know WHY they are unbootable even though they are readable.
So instead I will start over; for the gentoo installation, I want copy everything off of the partition and into another temp drive, rearrange the partition table and make it all nice again, and then copy it back (change fstab, /boot is already a seperate partition). This way I was hoping I wouldnt have to reinstall gentoo from scratch.
| neiljw wrote: |
No -use dd (man dd). |
I thought dd can make an image, but its not very flexible (it has to be put back in the exact same place on the disk or something). |
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NeddySeagoon
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Joined: 05 Jul 2003
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| Posted: Thu Nov 29, 2007 10:05 pm Post subject: |
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tsinghoi,
dd makes a low level image, ignoring the filesystem and copying any empty space too.
dd images must only be restored to *identical* sized partitions or strange unwanted effects occur.
This is a wonderful learning opportunity. Since your partitions can be read, its unlikely that have suffered much damage.
What errors do you get when you try to boot ?
If you get error messages from grub, thats usually a case of fixing grub.conf. If you want to learn a little more about computers, post your grub,conf, and the output oftogether with your error messages
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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neiljw
Apprentice
Joined: 12 Nov 2007
Posts: 166
Location: Telford, UK
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| Posted: Thu Nov 29, 2007 10:09 pm Post subject: |
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| tsinghoi wrote: | | I thought dd can make an image, but its not very flexible (it has to be put back in the exact same place on the disk or something). |
dd makes a byte for byte copy of the source to the destination. Like I said, "man dd". 
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Be lucky,
Neil |
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neiljw
Apprentice
Joined: 12 Nov 2007
Posts: 166
Location: Telford, UK
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| Posted: Thu Nov 29, 2007 10:15 pm Post subject: |
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| NeddySeagoon wrote: | | dd images must only be restored to *identical* sized partitions or strange unwanted effects occur. |
dd doesn't actually know or care about partitions as such. As long as the destination is big enough to contain the source, there are no problems. Either source or destination can be a partition, file, whatever. dd just copies the bytes contained within the source until there are no more.
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Be lucky,
Neil |
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tsinghoi
n00b
Joined: 28 Sep 2005
Posts: 15
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| Posted: Thu Nov 29, 2007 11:44 pm Post subject: |
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| NeddySeagoon wrote: | tsinghoi,
This is a wonderful learning opportunity. Since your partitions can be read, its unlikely that have suffered much damage.
What errors do you get when you try to boot ?
If you get error messages from grub, thats usually a case of fixing grub.conf. If you want to learn a little more about computers, post your grub,conf, and the output oftogether with your error messages |
"this is a wonderful learning opportunity" - haha, thats what I thought 2 and a half weeks ago when I screwed up my vista partition. I had the choice to delete the partition and install a fresh installation of vista, orrr try to fix it. I thought, "if I just reinstalled it, then I wouldnt learn anything!!" so I opted for the latter of the two choices. Well after screwing up ALL my partitions trying to repair that just one, I did learn things (like backup the MBR before you mess with it, and partition tables are a lot more complicated than I first thought), but not not the things I hoped to learn (like how to actually fix it).
I thought my OS's not booting up was just a problem with grub, but I think my grub.conf looks pretty much like how it used to (I had remake a boot partition) so it was weird. I'll take another look at it when I get home tonight. I'de still like to try to backup my partition before I screw it up even more lol.
| neiljw wrote: | tsinghoi wrote:
I thought dd can make an image, but its not very flexible (it has to be put back in the exact same place on the disk or something).
dd makes a byte for byte copy of the source to the destination. Like I said, "man dd". |
I did man dd, but im not very good at reading man pages. they used several terms that I dont know enough about yet, so it would take quite a bit of time to get through it... Ill try reading it again later. |
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