Fallback is the mechanism to maintain a duplicate copy of data managed by a different amp.When a Vproc(AMP) goes down during a load process the data is written to Fallback AMP.Once the down AMP comes online the Data is rebuilt using the FallBack AMP.
Journaling is another important feature in teradata.During a transaction teradata would maintain a copy of before or after images of table data .If the transaction fails due to any reason the table is restored back to the point from where the data images have been maintained.
However,Fallback and Journaling are expensive in terms of storage and maintenance.
Based on the discusson above...I understand that Permanent Journals and Fallback are independent of each other .There is no dependency as such on each other.... i.e
a) we can have P.J with out fallback..
b)similarly Fallback with out a P.J ..
Please correct me if i am wrong or add some thing here.
I am using TD 12. When i created a user via TD Administrator, i saw in the create user script fallback and permanent journal options are available. This means that all the fallback, PJ are applicable to user level also. Are these the data integrity measures at user levels? Please advise.