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Old 10-03-2007, 01:10 PM   #1
y2kram
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Disaster Recovery Plan


I will be migrating a host from SuSE 9.3 to Oracle Enterprise Linux.

Before doing it, I'd REALLY like to have a solid backout plan that will allow me to go back to where I was before the upgrade (or downgrade depending on your viewpoint).

I am looking for a way to take the existing system and make a bare metal recovery image of it (iso images?) that can be booted from and have a system restored exactly the way it was.

Anybody have experience with this... more importantly, anybody have experience actually having to use the bare metal image to go back to the previous system?

TIA!
 
Old 10-03-2007, 01:33 PM   #2
jailbait
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Quote:
Originally Posted by y2kram View Post
I will be migrating a host from SuSE 9.3 to Oracle Enterprise Linux.

Before doing it, I'd REALLY like to have a solid backout plan that will allow me to go back to where I was before the upgrade (or downgrade depending on your viewpoint).

I am looking for a way to take the existing system and make a bare metal recovery image of it (iso images?) that can be booted from and have a system restored exactly the way it was.

Anybody have experience with this... more importantly, anybody have experience actually having to use the bare metal image to go back to the previous system?

TIA!
I recommend Mondo.

http://www.mondorescue.org/

I also recommend that you experiment with backing up and restoring a non-critical hard drive before you use Mondo on your production system.

-----------------
Steve Stites
 
Old 10-03-2007, 03:44 PM   #3
uselpa
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I prefer a solution of
- A Live CD
- an external harddisk
- rsync as a copy tool.

I've moved whole installations like this without any trouble; just make sure rsync copies all file attributes.
 
Old 10-03-2007, 05:22 PM   #4
terryxela
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This is a 3 steps process:

1. you need a basic linux to boot the system. I use poppy linux in a usb flash disk (or dsl-n linux). You can use any of the live cd or the recovery cd of your distro. I use the same system to backup/restore. So to backup I boot linux from the poppy usb and backup to a usb attach hard disk. To restore I boot from the poppy usb and restore from the usb attached HD

2. Tools to backup.

DD it works very well. If you have two partition you will have to use dd for each one. It does not go accross file systems or partition.
For recovery you reverse the process and you are done.

tar or cpio. It allows you to have all partition in one file. The restore will restore to each partition.

3. If you use tar you will have to restore grub stage1 otherwise it will not boot. If you use dd you will not need it because it will produce an exact copy.

If you want to go in this direction first create some linux to backup. Look at poppy and dsl-n both are very small and very easy and fast to install. After you hve it please post if you need any help to run dd or tar.

-=terry(Denver)=-
 
Old 10-04-2007, 11:37 AM   #5
y2kram
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Quote:
Originally Posted by terryxela View Post
This is a 3 steps process:

DD it works very well. If you have two partition you will have to use dd for each one. It does not go accross file systems or partition.
For recovery you reverse the process and you are done.-=terry(Denver)=-
The system disk is carved up into 6 partitions total (sda1 thru sda6). What I'm testing right now is to try and do a dd of the entire drive (sda).

Boot linux from CD
mount a large NFS volume
dd if=/dev/sda of=/nfs-mount/sdafile

But you're saying this won't work with dd?
 
Old 10-04-2007, 12:44 PM   #6
uselpa
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I advise against the use of dd. It takes too much space and is filesystem-bound. A plain tar or rsync is much more flexible.

Last edited by uselpa; 10-04-2007 at 02:41 PM. Reason: typo
 
Old 10-04-2007, 01:27 PM   #7
swampdog2002
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Just out of curiosity, could you use rsync on all files in all partitions of a drive, and save them into on tar file? Basically, just save a copy of /dev/hdb and move this to /dev/hda as y2kram was attempting to perform in a similar fashion? I was reading this post, and I actually plan on performing a similar type of task, where I would like to move the entire contents of /dev/hdb (openSuSE 10.2 installation) and move them to /dev/hda. Or, would it be possible to simply replicate the same partitions on /dev/hda, along with file system structure, as those found on /dev/hdb and move the partitions this way? For example, save tars of /dev/hdb1, hdb2, and hdb3, and move them to /dev/hda1, hda2, and hda3, respectively?

Last edited by swampdog2002; 10-04-2007 at 01:28 PM.
 
Old 10-04-2007, 01:32 PM   #8
uselpa
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Assuming that hda and hdb are on the same physical machine, just boot a LiveCD, create a filesystem (any, not necessarily the same) on hda* and cp -a hdb* to hda* one by one. Adjust /etc/fstab, mess around with the boot manager and off you go.
 
Old 10-04-2007, 01:48 PM   #9
y2kram
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Plan B is using Partition Image (partimage) which is on the SystemRescueCd.

Boot the CD
mount the NFS volume for backup
create a backup image of each partition

But I believe the original plan gets everything, including the MBR, etc.

The oblective is:
If the new OS fails to do what it needs, I can boot the CD, mount the NFS volume, then dd the image back and I haven't lost a single byte off the spindle from where it was before the upgrade. That's why I'm trying the dd of /dev/sda as a single large image file.
 
Old 10-04-2007, 02:09 PM   #10
tkmsr
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grab a second hard disk
dd if=/dev/hda1 of=/dev/hda2

now use this second hard disk to upgrade degrade experiment what ever you wish your data on disk 1 is untouched
if the experiment is successful you can use disk 2 further
use disk 1 as primary backup
 
Old 10-04-2007, 02:41 PM   #11
y2kram
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Quote:
Originally Posted by tkmsr View Post
grab a second hard disk
dd if=/dev/hda1 of=/dev/hda2

now use this second hard disk to upgrade degrade experiment what ever you wish your data on disk 1 is untouched
if the experiment is successful you can use disk 2 further
use disk 1 as primary backup
Wish it was that easy... the system has 4 drive slots (and 4 drives!) 3 drives striped @ raid 5 w/1 hot standby. The expensive solution is to buy 3 new drives and save the original 3 "just in case". So that option really would be the last resort.
 
Old 10-04-2007, 02:46 PM   #12
uselpa
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Quote:
Originally Posted by y2kram View Post
Wish it was that easy... the system has 4 drive slots (and 4 drives!) 3 drives striped @ raid 5 w/1 hot standby. The expensive solution is to buy 3 new drives and save the original 3 "just in case". So that option really would be the last resort.
One more reason NOT to use dd.
cp and rsync let you move to a non-LVM environment.
 
Old 10-04-2007, 04:11 PM   #13
y2kram
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Quote:
Originally Posted by uselpa View Post
One more reason NOT to use dd.
cp and rsync let you move to a non-LVM environment.
It's a H/W raid group (not S/W Vol group).

The filesystems on the current system are reiser and the new filesystems will be ext3. If I have to restore everything, it must go back exactly the way it was. I don't want just the contents of the partitions, I want the disk structures as well so all I have to do is dd it back and reboot.

It's a critical server (part of a 4 node production Oracle RAC cluster) and I won't have a lot of (ie; any) time to figure out why it isn't coming back up after a restore.

Space isn't an issue, I have a 1TB NFS volume just for this back-out plan.

I guess it boils down to: what would be more solid or more reliable, and introduce less opportunities for problems, than a dd of the entire disk?
 
Old 10-05-2007, 09:35 AM   #14
y2kram
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Test result:

After dd'ing the entire disk to an NFS mount, I deleted a couple of partitions (using fdisk) and wrote/saved the partition table. Verified that the partitions were gone by looking at /proc/partitions.

Then mounted the NFS volume back on the system and did a dd back of the image to the /dev/sda disk.

When I looked at the /proc/partitions, I saw that the partitions I deleted were still missing, so I went into fdisk and listed the partition table (p) and saw that all 6 partitions were back, so I just wrote/saved it (w) and /proc/partitions shows that they were all restored.

Rebooted and the system came up.

Looks like this is a fairly solid solution to image the entire disk.
 
Old 10-05-2007, 09:44 AM   #15
y2kram
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Quote:
Originally Posted by swampdog2002 View Post
Or, would it be possible to simply replicate the same partitions on /dev/hda, along with file system structure, as those found on /dev/hdb and move the partitions this way? For example, save tars of /dev/hdb1, hdb2, and hdb3, and move them to /dev/hda1, hda2, and hda3, respectively?
"partimage" is a good tool if all you want are the actual partitions. But the target disk partition must already be defined (using fdisk?) and must be at least the same size (or larger) than the original in order to restore the image to that partition.

There is a copy of partimage on the SystemRescueCd (http://www.sysresccd.org/Main_Page)
 
  


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