restoring backup-image to unformatted 1.disk of a "2disk RAID1-array"

[hardware55]

Hello,

the 1st. disk of a "2disk RAID1-array" is broken and has
to be replaced. There are 2 paritions on that disk (CNTFS)
and DNTFS).

Should rebuilding and repartitioning the RAID be done under
every circumstance before restoring a backup-image to the
1st. disk of that "2disk RAID1-array" , or can the backup-image
directly be restored to disk ?

2.
Does it matter if we are dealing with partition-backup-images
with backup-images of whole disks?


Any tip is appreciated very much. Thank you!

John

 

[Arno Wagner]

Hello,

the 1st. disk of a "2disk RAID1-array" is broken and has
to be replaced. There are 2 paritions on that disk (CNTFS)
and DNTFS).

Should rebuilding and repartitioning the RAID be done under
every circumstance before restoring a backup-image to the
1st. disk of that "2disk RAID1-array" , or can the backup-image
directly be restored to disk ?

If this is a RAID1 array, then you put in the new disk
and start the RAID resync process. Not partitioning
or data restoration needs to be done. That is the whole
point of RAID1. Actually the system should not allow you
to resore an image to an individual disk at all,
since that would destroy the RAID array.

2.
Does it matter if we are dealing with partition-backup-images
with backup-images of whole disks?

You should not be dealing with images at all!

Any tip is appreciated very much. Thank you!

Just add the disk and tell the controller to add it to the
existing (degraded) RAID1 array.

Arno

 

[hardware55]

If this is a RAID1 array, then you put in the new disk
and start the RAID resync process. Not partitioning
or data restoration needs to be done. That is the whole
point of RAID1. Actually the system should not allow you
to resore an image to an individual disk at all,
since that would destroy the RAID array.


You should not be dealing with images at all!


Just add the disk and tell the controller to add it to the
existing (degraded) RAID1 array.

Arno

Thank's Arno for the tips. Very interesting things to know..

But let's say the disks are working fine, but i recognize
that i destroyed the operating system myself (e.g.
misconfiguration).

Is there really no way to restore an operting system partition
to an earlier stage?
(If i dont have to money to buy additional 3-4 additional disks
in order to use them only as backup-devices. In addition i
would be affraid that as soon a backup-disk would be inserted
the RAID-Adapter would start the rebuild-process and therefore
overwrite the backup-disk with the "bad/miscofigured-os-disk")


Again any clarification is appreciated very much. Thank's

John

 

[Arno Wagner]

Thank's Arno for the tips. Very interesting things to know..

But let's say the disks are working fine, but i recognize
that i destroyed the operating system myself (e.g.
misconfiguration).

Is there really no way to restore an operting system partition
to an earlier stage?

And where should that earlier stage data be stored? One thing
you can do: Do a backup to a separate partition. That makes
loss of the OS at least less likely. The only other solution
without additional storage is reinstallation form the original
distribution media. All other solutions need additional,
independent storage media.

(If i dont have to money to buy additional 3-4 additional disks
in order to use them only as backup-devices. In addition i
would be affraid that as soon a backup-disk would be inserted
the RAID-Adapter would start the rebuild-process and therefore
overwrite the backup-disk with the "bad/miscofigured-os-disk")

RAID1 is _not_ a backup solution! You need to do backups in
another way. RAID1 is solely used for protecting a system from a
single disk failure. It is not intended to protect against user
error at all. Your fears are perfectly justified.

On the other point: If you do not have the money to buy backup
medie, then you do not have the money to operate your computer
in a reliable way. Sorry, but there is _no_ way around this.

Again any clarification is appreciated very much. Thank's

No problem.

Arno

 

[Peter]

Thank's Arno for the tips. Very interesting things to know..

But let's say the disks are working fine, but i recognize
that i destroyed the operating system myself (e.g.
misconfiguration).

Is there really no way to restore an operting system partition
to an earlier stage?
(If i dont have to money to buy additional 3-4 additional disks
in order to use them only as backup-devices. In addition i
would be affraid that as soon a backup-disk would be inserted
the RAID-Adapter would start the rebuild-process and therefore
overwrite the backup-disk with the "bad/miscofigured-os-disk")

You don't need to buy additional 3-4 disks to use them as a backup.
One disk with sufficient capacity will be enough.
For smaller amount of data, DVD burner, stack of DVD-R's and plenty of time
might work as well.

 

[J. Clarke]

You don't need to buy additional 3-4 disks to use them as a backup.
One disk with sufficient capacity will be enough.

Until it breaks. There should be multiple generations of backup on
different physical media. How many and how far separated depends on how
secure you need to be.

 

[Arno Wagner]

Peter wrote:

Until it breaks. There should be multiple generations of backup on
different physical media. How many and how far separated depends on how
secure you need to be.

Two is the theoretical minimum. The idea is that when you do a new
back-up you break one old one, i.e. if you have two and discover a
problem during backup, you still have one good backup left. However
I think that three is the minimum you should have. You may want
more, depending on your needs, just as John says.

Arno