Skip Unused Blocks Issue in v9.4

Product version: 10.0.1

Last modified: 26 August 2020

Problem

In rare cases, the Skip Unused Blocks feature in v9.4 could skip incorrect data blocks, which resulted in corrupted backups or replicas. 

Background

The Skip Unused Blocks feature can skip incorrect data blocks on Windows based-machines with the NTFS file system, which may result in corrupted backups or replicas. 

The following backups and replicas are not affected: 

• Backups and replicas made with NAKVIO Backup & Replication v9.3 and earlier Product versions

• Backups and replicas of Linux-based machines

• Backups and replicas of machines using only Dynamic disks 

• Backups and replicas of disks that contain only 1 partition 

Solution

To ensure new backups and replicas are consistent

Update NAKIVO Backup & Replication to v10.0 or later. A one-time data consistency check is required (it is suggested automatically on the first login after the update). When you enable the data consistency check, the backup/replication job will re-read some data on the source machines (which in most cases is not bigger than a couple of GBs) and make sure the data blocks are consistent. This is a one-time operation. Subsequent job runs will be performed normally. 

To check old backups

Backups and replicas made in v9.4 can be checked by instant recovering of the machines with Flash VM Boot and running a filesystem check tool such as chkdsk.