Thursday, June 20, 2013

Question: How does the new Selective Incremental Mode work? How do I implement?
Keywords: SI, selective incremental
Operating Systems: Linux

This new feature is now available on LONE-TAR v4.3.3.2 Download Now

 Video - Setting up a Master backup and Selective Incremental backup to a device

1. Enabling Selective-Incremental Mode for a device
2. How Selective-Incrementals work

Critical Notes

  • When enabling SI Mode, Selective backups will perform differently. Details below.


Enabling Selective-Incremental Mode for a device 

1. 	LONE-TAR ships with this feature disabled by default. To change this setting first get into LONE-TAR
	
Type the command:
# ltmenu
	Select Option 9 (Device Manager)
	Select Option 'E' to edit highlighted Device (Press ENTER to cycle through devices to edit) 
		Select Option 'Si' (Selective-Incrementals)
			when .... [ ACTIVE ]
			Selective Backup files will look like: Si-backup-Mon.ltar
			All Selective backups will be based on date of Last MASTER for this device


			when .... [ DISABLED ] Original Setting
			Selective Backup files will look like: S-backup-Mon.ltar
			All backups will be based on no date and backup inclusion list

2.	You can also modify this setting straight from the device library file /usr/lone-tar/ltar.dev

Type the command:
# vi /usr/lone-tar/ltar.dev
	Scroll down to the device you wish to edit.
		Look for the Device Variable LTMasterDate[x]

			If LTMasterDate[x]="0" then Selective-Incremental Mode is DISABLED.

			If LTMasterDate[x]="1" then Selective-Incremental Mode is ACTIVE.

 

How Selective-Incrementals work 

What Selective-Incremental means is you are taking a Selective style backup with LONE-TAR and incrementing the files being backed up from the last Master Backup of that particular device.

So if you backup to a RDX Storage drive, and turn on Selective-Incremental Mode all the Selective backups to that device will be based on the LAST Successful Master Backup date for that device only. If no Master Backup has been successfully completed, then the Selective backup will backup all included files based on no date stamp.

Rotation Example with Selective-Incremental Mode enabled:
M-backup-Mon.ltar
Si-backup-Tue.ltar
Si-backup-Wed.ltar
M-backup-Thu.ltar
Si-backup-Fri.ltar

Rotation Example with Selective-Incremental Mode disabled:
M-backup-Mon.ltar
I-backup-Tue.ltar
I-backup-Wed.ltar
M-backup-Thu.ltar
I-backup-Fri.ltar

Both rotation schemes do the same exact thing. However the SI mode allows to do this for multiple devices rather than just one device.

Also, SI Mode allows you to selectively pick which directories you wish to backup incrementally.


So if you have a crash, all you have to restore is your most current LONE-TAR Master Backup and most current Selective-Incremental Backup. Simple.

Details on how the Increment date is generated.

- 	When a Master Backup completes and bit-level verifies, LONE-TAR captures the date of the backup and posts the
	date to a file with the device number of the current backup device.

	Filename example: Master-date-device4 ... Master-date-device#
	
	Once Selective-Incremental Mode is enabled all selective backups for this device will look for that completion date
	and if that date exists, it will backup only the files that have been modified from that date and on.