Thursday, October 21, 2010

Fun with VSS

I get this call today, "Hey man, I did some stuff last night to some files. Can you take a full backup from around 9PM, just before I started, in case we need to pull something back?"

Now to protect the innocent, he knew we had VSS snapshots going so its not as bad as it seems... or is it? I poked around for awhile but didn't see anything in NetBackup that would allow me to target a specific VSS snapshot for a full backup. I started thinking; "sure, let me get in the hot tub time machine and knock that out!" But after a few searches later (maybe some of the same that brought you here) it was pretty straight forward to go back in time after all.

We start off with with finding a list of our shadows. We want to find the corresponding entry to the "Shadow Copy Volume" of the date/time we're looking for. It looks something like

E:\>vssadmin list shadows /for=e:

Contents of shadow copy set ID: {7f35f0eb-f654-47b2-9ec4-0be0b4d285bb}

Contained 1 shadow copies at creation time: 10/20/2010 9:00:21 PM

Shadow Copy ID: {00dc1abc-480c-47fe-8f70-2e1ee2c969ff}

Original Volume: (E:)\\?\Volume{31cb9b20-d098-11df-9830-00505688000d}\

Shadow Copy Volume: \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy534

Originating Machine: ******

Service Machine: ******

Provider: 'Microsoft Software Shadow Copy provider 1.0'

Type: ClientAccessible

Attributes: Persistent, Client-accessible, No auto release, No writers,


Next, we want to make a link to the shadow copy.

E:\>mklink /d e:\10_20_2010_2100hrs \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy534\

symbolic link created for e:\10_20_2010_2100hrs <<===>> \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy534\


Volume in drive E is corp

Volume Serial Number is E847-3199

Directory of E:\

10/21/2010 06:13 PM 10_20_2010_2100hrs [\\?\GLOBALROOT\Device


0 File(s) 0 bytes

10 Dir(s) 266,310,508,544 bytes free

Now we can point our backup solution to the specific folder within our snapshot that we want to archive for that rainy day. As a side affect, this seems to elegantly solve an issue doing backups on DFS shares (which this is), and allows for much easier restores. We'll post a follow on and cover that soon. Stay tuned!


Monday, October 18, 2010

What is NetBackup OST?

In recent years many intelligent storage devices targeted at backup and recovery have been introduced to the market. Examples include Data Domain, the Quantum DXI Series and Falconstor. These devices include advanced capabilities such as deduplication, replication, creating copies and writing directly to tape. The challenge has been that there was no way to coordinate these activities with the backup and recovery software. The appliance could make a copy to tape but the backup software was unaware of it. This meant that the backup catalog was incomplete. In addition the backup software had no way to manage the device or tell it to perform certain functions such as making a copy. Symantec developed OST to address these issues.

OST stands for OpenStorage Technology and at a high level it is an API that allows NetBackup Media servers to take advantage of intelligent disk devices as well as cloud storage solutions. Storage vendors that participate in Symantec’s STEP (Symantec Technology Enabled Program) are given access to the OST Software Developers Kit allowing them to create plug-ins that more tightly integrate their devices with NetBackup. The OST plug-ins are provided either directly from Symantec or from the storage manufacturer and installed on NetBackup Media Servers.

The vision for OST was announced in 2006 and made available in NetBackup 6.5. Most recently Symantec included OST functionality in Backup Exec 2010 – calling the capability simply Symantec OST. Although both features are called OST there are separate Hardware Compatibility Lists for OST support in Backup Exec and NetBackup.

The OST API is protocol independent, meaning the hardware providers can utilize OST over whatever protocols are best suited for their devices including Fibre Channel, TCP/IP or SCSI.

The OST API provides 4 key features but the hardware vendors are not required to support all of them but rather just select the ones most suited for their devices.

OpenStorage Features

  • Direct Copy to dedicated tape drives
  • Direct Copy to shared tape drives
  • Optimized Duplication
  • Optimized Synthetics

One manufacturer that has strongly embraced OST is Quantum with their latest DXI Series appliances supporting both Optimized Duplication and Direct Copy to Shared Tape Drives. Using these features Quantum is able to replicate between DXI appliances or backup directly from a DXI to a tape library all while keeping NetBackup aware and the catalog consistent.

Depending on the intelligent storage device in use OST may also provide better performance than a standard Fibre Channel or NFS/CIFS interface. The OST API allows the vendors to coordinate communication and data transmission between the media server and the storage device in a way that traditional access methods cannot. The storage manufacturers can also leverage this technology for load balancing.

The list of manufacturers supporting OST continues to grow as do the ways in which they are taking advantage of it. As to how you get OST there are a number of pieces involved.

  • NetBackup includes OST as part of the Enterprise Disk Option and is licensed based on the Front End Capacity.
  • Backup Exec includes OST as part of their Deduplication Option licensed per media server.
  • The storage manufacturers typically offer OST support as an additional cost item.

The following link will take you to the Symantec OST page where you can also find the NetBackup Hardware compatibility list including OST supported devices and the specific features supported by each.

Symantec OST Home Page