VSS Backup Details

[Madhusudana_D]

Hi All,

In our environment we are planning to take a backup of Windows 2003 & 2008 servers backup using VSS instead of VSP.

Can you please help me with the below questions, so that will explain this to our windows team and then will change it to VSS.

1>VSP is needed 20 % of free space on each drive to take a backup and how much does VSS backup take?
2>VSP backup creates a VSP cache file on each drive and similarly which file does VSS create and how much % of free space required to take backup?
3>what are the advantages of VSS over VSP in terms of space utilization for cache files?
 

Master Server : Solaris 10

NB Version : 6.5.4 & 6.5.6

Thanks,

Madhusudana D

[Mark_Solutions · Accepted solution]

I hope I can give you some guidance, although a lot of this is Windows rather than NetBackup:

Firstly, for 2003 and especially 2008 VSS should, if not must be used.

1. VSS space usage is controlled by VSS itself in the servers advanced properties - all based on its Shadow Copy Components

2. VSS works in a difefrent way using the Shadow Copy sections - again as specified on the server itself

3. VSS is required for System State / Shadow Copy Component backups and will be used for these regardless of the setting you make within NetBackup (So you are already using it to some extent). It is far more integrated in to the Operating System itself and runs without the snags that are regualrly encounted using VSP (especially those left behind cache files)

Bear in mind that 6.5 goes end of life in just 4 months time so you should be looking to upgrade to 7.1 or 7.5 when you will find that VSP no longer actually exists so will not have a choice when your time comes.

Have a google for Volume Shadow Copy service and see all of the definitions on the Microsoft based sites for full details of hw it is controlled. NetBackup will simply call it - how it is controlled is down to your server setup

Hope this helps

[Nicolai]

This link will explain the default VSS settings Netbackup 6.5.4-> 6.5.6 uses:

After upgrading to NetBackup 6.5.4, adjustments may be made to Windows VSS settings that lead to individual snapshots being deleted unexpectedly on a Windows client. This affects snapshots that are taken outside of NetBackup manually or with a third party application

http://www.symantec.com/docs/TECH72361

Addition to Mark fine post: VSS is a copy on write technology. If new data block isn't written to disk while backup run the space usage is close to none. If you have HUGE amount of I/O's the VSS space usage will also be huge.

[Omar_Villa]

There are several reasons of why a Windows OS Snapshot fails and tons of Microsoft patches, the best way to figure this out is to run a OS Snapshot to remove NBU from the equation, this will tell you if is VSS or a specific Windows File System that you are failing to backup, a quick way to figure out which File System is the problem run a multistreamed backup and look for the one that fails, from there use the Windows 2008 backup tool to backup the File System that fail (http://technet.microsoft.com/en-us/library/cc770266(v=ws.10).aspx) and check on the Windows Event Viewer and you find more info about your issue, you can google that error or post it here and I'm sure it will give you a better light of what you need that most of the time leads to a specific windows patch.

Hope this helps.

Regards.

[Madhusudana_D]

Thank you Mark, Nicolai & Omar