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Troubleshooting Status Code 156 "snapshot error encountered" occurs when using VSS for Open file backups or snapshots

Article: 100005783
Last Published: 2020-12-09
Ratings: 10 5
Product(s): NetBackup & Alta Data Protection

Problem

When using "Windows Open File Backup" option in NetBackup for a Windows client which uses VSS snapshots and backup fails with status code 156 "Snapshot error encountered"

Error Message

Status 1

Status 13

Status 156

Cause

VSS maximum snapshot sizes are not set correctly.

3rd party Database Backup Utilities are dumping to file during NetBackup file level backups

Solution

Examine NetBackup Administrative console, Activity Monitor details to determine if the file is a database dump to text file. If so reschedule backup and database dump to non-conflicting time window. If backing up open files is not required or you do not have enough disk or memory resource you can uncheck the enable windows open file backups tab under

Host Properties >  Master >  Properties - Client Attributes- select client (or Add Client if not there) > Window Open File Backup

Select "Use Microsoft Volume Shadow Copy Service (VSS) (Windows 2003, XP SP2 or later)"

 

Also determine other aspects of the failure: 

# How large is the partition you are trying to backup?
# How much disk space is free on it  and the other partitions off the system?
# As a rule of thumb 10% of partition should be allocated to maximum snapshot size.

 
To modify/verify VSS setting on the Windows client run the following commands at the command prompt:
 
vssadmin list providers                          This should list Microsoft, if others are listed they may need to be configured
                                                                   properly or removed   See 100006056 link below
vssadmin list writers                               The writers should be stable with no error.
vssadmin list shadowstorage                As a rule of thumb set 10% of partitions  size to VSS maximum cache size.
 
Windows System and Application event logs will also show VSS and VOLSNAP errors that can help determine the reason behind the error
 
VSS maximum cache size  and partition selected  is set from the Windows Explorer GUI on the client.  Go to:
Windows Explorer Select the drive (C:), Properties, - Shadow Copies tab - Select Partition - Select Settings.
This will allow you to increase the size and partition for the snapshot.
 
 
Please Note:
The default setting in the Shadow Copy GUI is disabled for each partition. Do not modify this as it will start OS initiated snapshots independent  of NetBackup
The default setting for the Microsoft Provider and Volume Shadow Copy Service (Manual) is sufficient.

Related Knowledge Base Articles:

 
 

Applies To

Applicable to all versions of Windows Operating System which have been Qualified for Support with NetBackup.

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