Attunity MS-SQL 2000 CDC solution – All runtime component on a single machine – why?
Standard defaults proposed for a CDC solution introduce a ‘Two machines’ assignment.
Applying these defaults for an MS-SQL CDC solution is inappropriate.
Recall that if the staging area machine is not active for a certain period of time, CDC processing is exposed to a potential threat of losing events.
Since transient storage is of limited size – events held there should be consumed within a reasonable period of time.
If they are not – they may be subjected to a cleanup procedure launched as volume threshold is reached.
There is nothing new in this notion.
At any point along the data propagation path - starting at the transaction LOG, through the transient storage, ending at the Staging Area- data availability is limited in terms of space and / or time.

Adopting a ‘single machine’ assignment considerably reduces these potential threats – since – either all CDC runtime components are active or none of them is.
Selecting the machine in which the MSSQLserver itself is running provides a full ‘All or Nothing’ coverage.
For similar reasons – one is warmly advised to avoid from specifying ‘shared device’ at other machines as transient storage location.