Difference in Disk Utilization

I'm currently working on a KB article to list reasons why you may see capacity usage differences between an Avamar source and target..

It isn't yet complete but hopefully this will help you out.  English/English spelling used..

Symptoms

There is an Avamar source and an Avamar target system.  Capacity utilisation is higher on one system than the other

Cause

An Avamar source replicates selected data asynchronously to the target system.  Replication occurs daily.  Provided that replication completes fully, each day we would expect that the data on the source system to be roughly a day 'behind' the data stored on the target system.

Replication is additive - systems are not kept synchronised, therefore, it is possible that the amount of data stored on the source and target systems may differ

Reasons for possible differences between the 'server utilization' values could be:

Physical / logical differences between the actual grids

• There may be a different      number of data nodes on the source and target system
• The data nodes on the      source system may not have the same disk configuration (1TB, 2TB, 3.3TB,      etc) as on the target system

• Stripe distribution across the data nodes of each system are adequately balanced (to within 2%)

• Storage and parity      requirements may differ between Avamar versions.  A difference in the utilisation level may      be observed if the grids are not running the same software revision

Configuration differences

• Backups replicated to the target system may be configured to have a different retention policy than the same backups which exist on the source (refer to the 'expiredelta' flag for more information)
• Replication may be configured to replicate only a subset of clients from the source system to the target system if include or exclude settings are used within the replication configuration
• Clients and their associated backups may have been deleted from the source system.   The deletion of a client or of backups on the source will not remove the same backups from the target system.  The backups will remain on the target system until they expire according to their retention settings.

• Retention policies may be      changed for backups or clients on the source system.  The change in      retention policies will affect new backups only.  Any new backups      will be replicated to the target and will adhere to the updated      retention policy but any backups already existing on the target will      retain the retention policy which was applied to them at the time they      were replicated to the target.

Unexpected behaviour

• Cross replication may be      occurring between multiple Avamar systems.       The source Avamar grid may also be receiving replication data from yet      another source grid or the target grid may be the target of more than one      Avamar source.
• Replication may not be up      to date and the target may be 'lagging behind' the source by more than one      day.