Creating Consistent Point-in-Time Backups

Home  Previous  Next

Some programs may write some data on the disk while R-Drive Image is creating a data backup. To avoid data inconsistency, R-Drive Image uses two mechanisms for creating consistent point-in-time backups.

Windows XP, Windows Server 2003, Windows Vista, and later

R-Drive Image uses Microsoft Volume Shadow Copy Service (VSS) to notify other applications supporting this service that it is going to start a data backup process in order for them to flash all necessary data to the disk. Most applications like Microsoft Exchange Server, Microsoft SQL Server, and Oracle software support this service.

Options Windows Volume Snapshot Service and Notify system application on the Backup Options panel enable/disable the use of this service.

If a software that does not support VSS runs on your computer, you may use Backup AUX applications and Snapshot AUX applications on the Backup Options panel (and their respective commands/parameters in scripts) to send special commands to your application that will make that application flush its data to the disk before the backup process starts.

Windows 2000 and earlier

R-Drive Image uses its own driver to create a file system snapshot but it does not notify other applications that it is going to start a backup process. Therefore, if an application stores some of its data in memory, they will not be saved in the backup file. To avoid data inconsistency, we recommend you to use Backup AUX applications and Snapshot AUX applications on the Backup Options panel (and their respective commands/parameters in scripts) to send special commands to your application that will make that application flush its data to the disk before the backup process starts.

Option R-TT Volume Snapshot Service on the Backup Options panel enables/disables the use of this service.

Click to expand/collapse Backup Options

If any of Backup AUX applications and Snapshot AUX applications are executed, the following environment variables are set:

R_CALLBACK_UID

A unique digital backup id used in all calls for external commands pertaining to that backup process.

R_CALLBACK_STAGE

Takes the following values:

BEFORE_BACKUP

AFTER_BACKUP

BEFORE_SNAPSHOT

AFTER_SNAPSHOT

R_VOLUME_NAMES

A comma-separated name list of partitions to be processed.

R_VOLUME_GUIDS

A comma-separated GUID list of partitions to be processed

Therefore, the same command may be used for all the fields provided it will determine using R_CALLBACK_STAGE in which context it is called.

Below is an example of the variables when disks C: and D: are being backed up:

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=BEFORE_BACKUP

R_VOLUME_NAMES=C:,D:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008},{9636e065-f75e-11dc-981a-829328f78201}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=BEFORE_SNAPSHOT

R_VOLUME_NAMES=C:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=AFTER_SNAPSHOT

R_VOLUME_NAMES=C:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=BEFORE_SNAPSHOT

R_VOLUME_NAMES=D:

R_VOLUME_GUIDS={9636e065-f75e-11dc-981a-829328f78201}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=AFTER_SNAPSHOT

R_VOLUME_NAMES=D:

R_VOLUME_GUIDS={9636e065-f75e-11dc-981a-829328f78201}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=AFTER_BACKUP

R_VOLUME_NAMES=C:,D:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008},{9636e065-f75e-11dc-981a-829328f78201}

 

Note: If the system settings permit, several disks may appear in one snapshot. Then the following calls will appear:

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=BEFORE_BACKUP

R_VOLUME_NAMES=?:,D:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008},{9636e065-f75e-11dc-981a-829328f78201}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=BEFORE_SNAPSHOT

R_VOLUME_NAMES=?:,D:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008},{9636e065-f75e-11dc-981a-829328f78201}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=AFTER_SNAPSHOT

R_VOLUME_NAMES=?:,D:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008},{9636e065-f75e-11dc-981a-829328f78201}

 

R_CALLBACK_UID=2008

R_CALLBACK_STAGE=AFTER_BACKUP

R_VOLUME_NAMES=?:,D:

R_VOLUME_GUIDS={d5f570a1-2978-11dc-83bf-005056c00008},{9636e065-f75e-11dc-981a-829328f78201}