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Consistent backup using script and vss

Created: 17 Nov 2011 | 1 comment

Hi there!

 

I have a little bit of a problem.

 

I have a process that continously writes to the disk and is not "shutdown aware".

That mean, if I use vss for backup, it is not sure that the data that has been written to the open file that the process use are consistent and can be used in the case of a restore.

 

So, what I have to do is to shut down or pause the writing when taking a backup.

 

However, it is not an option to have the process down during the whole backup time, it is way to critical to even think about that.. But, I have done some research on how netbackup is taking a backup in a modern operating system, and how it is handling open files and come to the conclusion:

1. Netbackup calls VSS

2. VSS creates a snapshot and move all current writers to the snapshot file, leaving the original disk in read only mode

3. Netbackup starts to backup the harddisk

4. When ready, netbackup tell the VSS to write all the new data from the snapshot to the disk and then delete the snapshot file.

 

What I want to do is something like this:

 

1. A script stops/pause the process that are writing

2. Netbackup calls VSS

3. VSS creates a snapshot and move all current writers to the snapshot file, leaving the original disk in read only mode

4. A script starts/unpause the process that are writing.

5. Netbackup starts to backup the harddisk

6.When ready, netbackup tell the VSS to write all the new data from the snapshot to the disk and then delete the snapshot file.

 

How do I do the above? Any suggestions?

Comments 1 CommentJump to latest comment

MKT's picture

At the VSS time, if there is no active writer to the data you have stopped I'm not sure that VSS would work the way you outline.  Once you start the process again and there are more active files you are going to hit issues.  I'd recommend looking at the Snapshot Client options and try to get a quick snapshot of the entire disk while the process is down and backup from the snapshot rather than try to time a Open File Backup.

 

Just my two cents.