Friday, October 11, 2013

Read Only Friday - debugging Volume Shadow Copy without rebooting a server

One of the most difficult challenges for us is to debug Backup Exec 2010 R3 failures. It seems like they are very frequent and it could be a full time job just keeping backups running! And you know it's Friday - we can't break anything before the weekend, so we have to be ultra careful with the 'god switch'. But, Backups are important to fix, even if they're hard - right?

Microsoft VSS is a technology that powers the 'previous versions' option on Windows file servers. It's pretty much a snapshot service like what you might have seen in another product (NetApp Filers for example), but its baked into Windows. So it doesn't take a lot of work to set a server up to create a backup copy occasionally. By default these snapshots happen at 7am and 12:00pm every day. But you can add or change the schedule to fit your needs.

VSS copies files even if they are currently open. So it also is used when making backups. Because that way the file does not need to be locked, released, or entirely skipped during a backup. Backup Exec has the ability to use the Microsoft VSS driver, but there is also an optional Symantec one available.

When backing up a system it is very helpful to have the Backup Exec Remote agent installed. Otherwise the backup just accesses the file through the usual file sharing methods. Backups with the agent can use VSS, and run much faster.

Troubleshooting backups that fail is very time consuming. Troubleshooting those that fail due to VSS has been pretty challenging! Here is a great blog post on the /misc/tech/musings blog that is really sweet!

Using this information allowed me to get VSS working on a profile server without restarting the machine. Good news on a Friday before a long weekend! (With thanks to Will for pointing me to VSS yesterday!)

No comments: