Best practice with AOFO?

[Tiemo]

Hello,
I am not that system guy and I didn't have setup my W2003 SMB Server with BackupExec 12, Rev 1364, but I have to keep it run and make a restore in case of
Now I am a bit unsure about AOFO and the snapshot technology in pratice, AOFO is activated and choosing the technology for AOFO is set to automatic. I have read the help files and some threads in the forums and I know roughly what is happening, but still unsure about the following and I don't want to experience that I have choosen the wrong option in the emergency case of restoring:
1. Are there any disadvantages using AOFO, like higher risc of restore faults as of standard full backups, or much more time or space consumption?
2. Does AOFO creates a snapshot of all files or only of the open files? If yes of all, is there a difference of a snapshot of a closed file to a "standard" backup of a closed file?
3. The existing DB on the server is shut down before backup, so actually the main open files are some Outlook personal folders (.pst) on the server (No, I don't have exchange installed, just put the personal folders on the server) and perhaps some minor single files.
4. What would happen to a pst, when saving without AOFO? Would it be corrupted, when resoring?

Thanks for any coaching or hint!

[Hemant_Jain]

1. For file level backup and restore, there is really no disadvantage as such of using AOFO. It is really helpful in backup of open files. in terms of time or space also, VSS is claimed to be faster by Microsoft, so that is really not an issue. So, for file level backup and restore, AOFO is definitely recommended.
2. Snapshot contains all the write activity coming to disk, while the backup is being processed. So, snapshot really does not contain data of an open file, only the changes that are coming to disk are written to snapshot, while the backup continues to run. So, size of backup is dependent upon the disk activity. I hope that clarifies!!
3. It is ideal to use AOFO to backup pst files to make sure you get a consistent backup.
4. There will be no corruption. MS recommends using VSS for backup of all files, and that really is the future. If you take a look at all OS after Windows 2003, they all have to use VSS, it is no more an optional thing.

So, use AOFO for file, folder backup without any issues. For database backups, though there are some known limitations of VSS, but nothing that can be called a data threat.

There are some more details for your reference in this article:
https://www-secure.symantec.com/connect/articles/advanced-open-file-option

Please mark it a solution, if this is useful.
Thanks
 

[Tiemo]

Dear Hemant,
thank you for your extensive explanation, that clarifies a lot. Though I have left two questions to your explanation open.
1. What is your recomendation in the AOFO Options: Should I keep the Option "Choose the technology automaticly" or should I choose "MS VSS" with "let VSS choose the snapshot provider by automatic"?
2. In your second point above I may have misunderstood: "So, snapshot really does not contain data of an open file, only the changes that are coming to disk are written to snapshot" If the snapshot does only contain the changes coming to disk - where is the "rest" of the file / the full backup of the file?

Thank you for clearifing
Tiemo

[Hemant_Jain]

Answers follow:
1. Leave it automatic, BE will use VSS if it encounters a Windows 2003 or above OS, as per recommendation from MS. For OS older than Windows 2003, VSS will not be used. So, automatic should work for you.
2. When backup job starts, snapshot is taken, which is just an image of current disk layout. Then the backup starts, and BE takes the data directly from disk and if there is any change request coming to disk, it gets written to snapshot file, while BE continues to do the backup withouth noticing any disturbance because of disk activity. Once Backup is completed, the snapshot file is commited to disk and changes are written. So, rest of the file, of course is on the disk and backup job backs up that data from disk. For more information, i would suggest you to do some more reading on "Copy on Write" mechanism used by VSS.

Thanks

[Tiemo]

Very helpful and clearyfing
thank you!

[Hemant_Jain]

Please mark it a solution, for others to use it as a reference.

Thanks