True Image Restores - What's the point?

[john0124]

Running 6.5

True Image Restore - After attending a recent NB training course I thought I understood the point of carrying out TIR restores; you can restore a file structure to exactly the state it was in at the time of a backup. However, upon carrying out some tests, I have found that I can do that just as easily with TIR not set on a policy.

As an example;

I create a new directory with several files in it.

Then I carry out a normal full restore (without TIR).

Delete a few files.

Carry out an incremental.

Next I go into the restore screen, and select the full & incremental backups that I’ve just run, from backup history. Under ‘Directory Structure’ I select the parent directory of the directory I created. Then in the ‘Contents of selected directory’ box I tick my directory. When I then highlight the directory in ‘Directory Structure’ I see that only the files that existed at the time of incremental backup are ticked.  If I then continue and actually do the restore (to an alternative target), the result is a directory identical to the original (at the time of the incremental).

This was the functionality that I thought I needed TIR for. I am probably missing something here, but would anyone be able to shed some light on why you really need TIR?

Thanks a lot,

John.

[J_H_Is_gone]

when you highlighted the full and incr  (are you doing diff or cumulative)
do you see the files you removed?
As they should be showing on the full backup.
so if you have the full and the incr both highlighted at the top you should see all the files from the full and any file that where changed on the incr will have a different date(time) - meaning you would be getting those

So what you should see

filea   date of full backup
fileb  date of full backup  (you removed this file before running the incr)
filec  date of incr
filed date of incr

[Luc_H]

Hi John,

The TIR information is only taken at the start of either Differential or Cumulative backups. The process involves taking a "snapshot" of which files are where in the volume being backed up. Using this information NetBackup can know which files have been removed (or moved) since the previous backup.

TIR information is used during the restores. If you perform a TIR restore, NetBackup will only restore files that were in the file system at the time of the last TIR backup. If a normal restore is done, all files are restored even if they were deleted between the time of the full and following incrementals.

Example:
Backups done: 1 Full, 1 cumulative and 2 diffs.
TIR restore: only restore files that were present at the last TIR diff from all images.
Normal restore: restore *all* files from the above images.

A normal restore will leave you with a much larger file system of which you would have to go back and delete all the files that should no longer be there.

You can find a good example in the Policy Attributes section of the NBU Sys admin guide vol 1.

I hope this helps.
Luc.

[john0124]

Thanks for the replies.

As I said, I do understand what TIR backups do.  But from testing it appears to me that non-TIR backups give the same level of functionality, just as easily.

Following the steps I detailed earlier, I do see all the file & directories, but it is only those that existed at the time of the last incremental that are selected by default.  therefore you can immediately click 'restore' and you have achieved exactly what you would have done had you used a TIR restore. Other files (those backed up in the full or an earlier incremental and since deleted or renamed) are displayed and are available for restoring if desired, but not by default.

Indeed I think you could argue that doing a 'normal backup' restore gives you more options because with a TIR restore you see only directories and not files; you have to restore all files in selected directories.

I think from you replies it does indeed look like there is no advantages at all in using TIR.

Thanks again,
John.

[J_H_Is_gone]

I believe both of us tried to say that you are doing something incorrect.

As there is a BIG difference between using TIR for backup/restore and doing Normal backup/restores

[john0124]

Thanks again for your reply.  I really do appreciate you taking the time to help.

Having spent 2 days looking at this I know I'm not doing something incorrect.  If you follow the steps I outlined in my first post you will see what I mean.

I was simply looking to find out if there is something extra that TIR offered that I wasn't aware of.

As I say, try out the steps and you will understand what I am talking about.

[Nicolai]

Have you piced the right restore type?  You won't see individual files when doing TIR restores, you only see directories.

[john0124]

Nicolai,

Thanks for the reply.  As I said, I have no problem carrying out TIR restores, my question was why are they required?  It's kind of funny that no-one is actually reading what I am saying.  I am not making a mistake, and if anyone cares to follow the steps that I outlined you will see what I am getting at!

Anyway, Thanks again.

[Andy_Welburn]

could you do this 'manual' TIR if your directory structure was more than just a single test directory with a few files? Maybe in the '00's or '000's or more?

Just a thought. ;)

[Nicolai]

Yes I read your'e post to quick - Sorry. I belive you can't obtain the same functionality without TIR because "normal" backup don't track moved and deleted files.  This doesn't mean what you are trying to show is wrong !! - You may get some of the functionality.

Try to run the following test, I dont think you can do the same with a normal backup without knowing the directory structure. It's written for UNIX but you should get the idea.

Issue the following commands
# mkdir /test
# cd /test
# touch a b c d
Run full Backup from GUI

Rename/remove selected files, and run incremental backup

#rm /test/a
#mv /test/c /test/cc

Run Incremental Backup from GUI
# rm -r /test

Run true Image restore of /test
List /test

The file a has been removed, and file c has been renamed, so the directory must contain the files b, cc and d.

[Andy_Welburn · Accepted solution]

Just came across the following T/N which may be of use:

TIR: Explanation, benefits & limitations