Application-aware…why you should care!

Application-aware Backups in the virtual world!

Many of today’s backup vendors are advertising that they can do application-aware backups. That’s great – but what does that exactly mean? Why would this be of any value to me and how will it help my organization? The answers to these questions are pretty straightforward and the added value to having application-aware backups can become invaluable!

Let’s start with, “What exactly are application-aware backups“?

Application aware backups provide added intelligence to interact with applications that reside on a server. This server can either be virtual or physical but for the purpose of this blog post we will focus on virtual. These applications could range from your enterprise software solutions all the way down to your small homegrown applications. The key here is the ability to interact with Microsoft’s Volume Shadow Service (VSS) so that it can be treated properly. In other words, application-aware basically is saying that we will be doing a transactionally consistant backup of applications such as SQL, Exchange, Active Directory, Sharepoint, and I’m sure many more could be added to the list here. The key for application-aware is really tied to the ability to tap into the vss writers.

If you run this command, you will have a sense for which applications are covered by being vss-aware.

vssadmin list writers

So what happens when we trigger these VSS Writers?

The triggering of VSS writers will start a VSS freeze, the backup solution will find out if there is a VSS-aware application running inside a VM. It then requests Microsoft VSS to create a consistent and reliable view of application data prior to taking a VM snapshot. Windows VSS interfaces with VSS-aware applications and Windows OS to quiesce all I/O at a specific point in time. This way, it ensures that there are no unfinished database transactions or incomplete application files during data copying operations.

What happens if I don’t backup in an application aware manner?

This method would be called crash-consistent and for most servers that don’t rely upon a database, it would suffice. Any server that has a vss-aware application residing on it will almost always prefer to be application consistent. One example, when you restore a domain controller that has been backed up in a crash consistent manner, the server feels as if it has experienced a hard shut down and then continues on to do an active directory repair. And for Microsoft SQL, you may need to know how to replay logs into a database file.

As you can see, not quiescing these applications/databases can leave room for data corruption and/or lost data. Protecting your systems in an application aware manner will ensure that all data residing on the virtual machine is protected and will be accessible upon a restore. Another great reason for application aware backups is the amount of time and frustration that it could save you by enabling this capability!


Enabling this feature within Veeam!


When creating a new backup job within Veeam, all that you need to do is hit the check box for Application Aware Image Processing followed by credentials and you’re off and running!

*Update* One extra benefit that I forgot to mention was Veeam’s ability to do log pruning for Exchange & SQL. The fact that Veeam is the only vendor that can do this at a image-level backup is extraordinary! See below on where to enable!  <– Thanks Doug Hazelman, @VMDoug!




Veeam & Rotating Media

Many organizations rely upon tape devices to off-site their backups which upon proper configuration can be very reliable. Well, what about the organizations that aren’t big enough to need a tape library? As always, Veeam has your BACK! Veeam added full support to leverage external hard drives (typically attached by USB) so customers can off-site their backups via USB HDD. Pretty cool!

In order to configure this capability, you will want to upgrade to Veeam v7 as well as install patch #3 (the patch is cumulative). This will enable full support for you to do rotating hard drives and can even choose to do this with both backup or backup copy jobs. If you’re not familiar with backup copy jobs then you should dig in and check this feature out! Here is a link with more details on backup copy jobs!

Some of you may be thinking, “This ability has been around for awhile with Veeam“. While yes, this is true, Veeam has added another piece to the process that will make life easier! So let’s jump into a few of the changes that need to be made to get this up and going.

(Assuming you have Veeam v7 already installed in your environment)

First, you will want to head over to Veeam’s website to grab patch #3 (

If you have version then you’re up to patch #3.


After getting patch #3 installed into your environment, there are just a couple registry keys that you will want to edit in order for this process to work as advertised. There is a bit of customization available by tweaking these keys which is what I like about it. The following 2 registry keys will need to be created in the location below in order for this to work.

Word of advice, “Always backup your registry before making changes!”

[HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Backup and Replication]

ForceCreateMissingVBK (DWORD)
Enables support for rotated drives. With this functionality enabled, if any backup file from the latest full backup chain is missing (such as when the existing hard drive is replaced by another one), jobs will start the new backup chain and create the new full backup (instead of failing out).
Set to 1 to enable support for rotated drives.

ForceDeleteBackupFiles (DWORD)   NEW!!!  <– This removes the need for scripting to clean up!
Enables automatic cleanup of the backup repository from ALL existing files if any backup file from the latest full backup chain is missing (such as when the existing hard drive is replaced by the hard drive brought back from offsite location, and containing some older backup files).
Set to 3 to make the job delete the entire contents of the backup job’s folder only.
Set to 5 to make the job delete the entire contents of the root backup repository folder, thus potentially deleting any files belonging to other jobs along. Note that if backup repository points at the volume’s root folder, the entire volume’s contents is erased.


After configuring those registry values, support for rotated hard drives will be enabled.

There isn’t any special process that you need to follow for creating either backup or backup copy jobs in conjunction with this feature. Simply add the rotating media as a repository within Veeam and have your backup or backup copy job write to this device and voila! Remove and replace for the next round. Upon the next interval of the job, the files will not be found and then a new full backup (VBK) will be created. -AB