KKB000858

 

SYMPTOMS

 

Backup log reports one or more of the following warnings: -

  • This machine does not have enough local hard drive space to copy backups sets for a synthetic full backup. As such, synthetic full backups will be performed over the network, which may decrease reliability.
  • This machine does not have enough local hard drive space to copy both the original and new backups sets for a synthetic full backup. As such, the original backup will be copied locally, and the new synthetic full backups will be created directly over the network, which may decrease reliability.
  • This machine failed to copy the old backup set to the local disk for synthetic backup. As such, synthetic full backups will be performed over the network, which may decrease reliability.

The warnings may be logged on the Backup client (source machine) or offsite server.

 

CAUSE

 

Synthetic full backups are created by consolidating the previous backup set (full plus incremental or differential files). Acronis does not support consolidation of backups on a network drive, so for backup clients with image location configured to a network drive Kaseya will check for local free space before starting a "synthetic full" backup: -


1) if there is more than 2x the total size of the backup set to be consolidated (in other words, the size of the last full backup plus all incremental or differential files): -

- the backup set is copied to the local drive
- the new syntehtic full backup is created on the local drive, then copied back to the network location after completion

This is the most reliable synthetic full backup method.

2) if there is less than 2x the total size of the backup set to be consolidated but more than 1x: -

- the backup set is copied to the local drive
- the new syntehtic full backup is created on the network drive

This is less reliable than the first method, because Acronis has to write to the network during consolidation.

3) if there is less than 1x the total size of the backup set to be consolidated, consolidation will be attempted over the network. This is the least reliable method, because Acronis must read and write from the network during consolidation.

 

SOLUTION

If the synthetic full backup is consistently successful, no further action is required. If the synthetic full backup sometimes fails, it will be necessary to make sufficient space available on a local drive for a complete backup set to be copied and the new full backup to be created.

To calculate the amount of data, review the last backup set and add together the file sizes for the full and all incremental or differential backups, then add to this the expected size of the new full backup.

 

APPLIES TO

 

Kaseya Backup