Well, We are now in 7.x version, but the people who travel from 3.x to 7.x, something confused in Delta mechanism. Here I am trying to give you brief idea about this. This document you can refer when you are confused at any time.
Here are 3 different scenarios with screenshots and step.
What we will see here?
In older version we use Infosource and infopackage to load the delta from one Cube to other cube but in 7.0 onwards we use DTPs.
Also, if there is a need to delete the delta and reload then there is a huge change in approach.
Here we will see how we load the delta from one source to other source in two different ways i.e. Old version and new version.
The Scenario
Here we will take one senerio in which we will load the delta from one source to other i.e. from one cube to other cube. We will also delete the delta and try to load it again and will see what is the difference between two approch.
Scenario 1 - Delta Load from one Cube to other in 3.x
Here we will see how we manage Delta in 3.x with the help of Infosource. We are using two cube. “CAPEX Allocated on Network Product Area – ZCAPKEY” and “Cognos 2007 onwards- ZCOG_C03”. We will load delta from ZCAPKEY to ZCOG_C03.
In 3.x we use inforsource and infopackage to load the data from one cube to another cube.
Step 1:
Here we are assuming that we have already done with init.

Step 2:
Now, we will upload the delta from ZCAPKEY Cube. For this we will find the Infosource and then we will run the infopackage for that Infosource. Infosource is created with the same cube name starting with 8. In our case the cube name is ZCAPKEY then Infosource will be 8ZCAPKEY.

Step 3:
Create an InfoPackage with Delta in Update tab and Schedule it.

Step 4:
Check the data in cube ZCOG_C03. Transferred Record should be same as Added records in cube ZCAPKEY.

Step 5:
Check data in cube ZCAPKEY, if the data is same or not. In our case it is 150 records.

Here we completed the delta load at second level. Now the issue is how to manage delta if we want to delete it and load it again? Below you will see how to reload the delta if it is failed or for any reason you want to reload it again.
Scenario 2- Delete Delta and Reload it again. Delete Data Mart Status.
Step 1:
Delete data from cube ZCOG_M03. Do not delete the init. Otherwise you have to init first and load the data with init.

Step 2:
Delete the data mart in ZCAPKEY. To do this go to ZCAPKEY and click on data mart button.

Step 3:
A new window is open. Click on delete button.

Step 4:
It will ask your confirmation. Click on yes and it data mart will gone.

Step 5:
Check data mart symbol and it is gone.

Now you can follow the same steps to load the data in Scenario 1.
Scenario 3- Data Load from one Cube to Another in 7.x.
In 7.x version and 3.5 onwards, Data can be loaded by DTP as well. You need to create the transformation and then the DTP. You can just run the DTP and data will be loaded.

To delete the data there is no need to delete the data mart status manually. You can just delete the request and reload it again.
So, here before you loading data at any stage and confused how delta Machenisam will work, you can read this and guess.
Please provide your knowledge in this Blog so me and other readers can get the benefits.
Cheers