If we have BAR and EMC data domain will it record changes only on next backup once you have one full backup or how it works as we are facing a long backup window time ? how that can be reduced and how the companies setup their backups with 10 or 20 or 30 TBs. We are taking 15 to 20 hours just for 3 TB. Please help in this regard.
The EMC Data Domain appliance is a backup storage target ie.
Like all layered solutions theyneed to be viewed holistically, if you current backup and restore solution is being constrained by other factors adding/increasing the backend storage will probably make little to no difference.
Backups to Data Domain from databases usually have fairly low deduplication rates and Teradata's MPP can work against the deduplication process which is why real world performance numbers can vary wildly from the Teradata estimated values for Teradata Advocated BAR solutions with Data Domain.
Highly volatile/new data and/or non-compressible data (eg. BLC with DSA) work against the Data Domain process
Client side type incremental solutions would be the worst for deduplication devices since in theory the majority of the backup would be made up of unique data
Two of the major variables in Teradata BAR that can directly affect performance;
If BAR performance is the question using Data Domain (where do I start), here's something you could try
Check for any blocking (the thing with DD - they do dictionary first and there might be some contention out there)
The performance of backup and restore are influenced by variety of other factors.
Number of streams, how you created the jobs, how many jobs you are running in parallel (I heard that practically you can't run more than one :-)).
Lastly the H/W itself.
15 to 20 hours for 3 TB is very bad throughput.
I suggest you to talk to your Teradata Rep as soon as possible.
Subsquent backups are faster because of the deduplication because they write less data (subject to the rate of change in the data).