RDF/IMP and IMPX System Management Manual (RDF 1.4+)

Network Transactions
HP NonStop RDF/IMP and IMPX System Management Manual—524388-001
13-9
The Effects of Undoing Network Transactions
The Effects of Undoing Network Transactions
Within an RDF network environment, phase 3 undo processing usually results in other
transactions being undone on every system in the network because the RDF product is
designed to make the safest, and most conservative, assumptions regarding all
possible interrelationships between transactions. This is best illustrated by example.
Consider an RDF network consisting of two RDF subsystem configurations (primary
system \A protected by backup system \X, and primary system \B protected by backup
system \Y). Assume that network transactions originate on both \A and \B, and that
they update data on both \A and \B. Assume further that each system also executes
local, non-network, transactions.
More specifically, assume that system \A (the network master) executes the following:
1. T
10
(network transaction started on \A)
2. T
11
(non-network transaction)
3. T
11
commit
4. T
10
commit
5. T
12
(network transaction started on \A)
6. T
12
commit
7. T
13
(network transaction started on \B)
8. T
13
commit
9. T
14
(non-network transaction)
10. T
15
(network transaction started on \A)
11. T
14
commit
12. T
15
commit
At approximately the same time system \B executes the following:
1. T
10
(network transaction started on \A)
2. T
20
(non-network transaction)
3. T
12
(network transaction started on \A)
4. T
13
(network transaction started on \B)
5. T
21
(non-network transaction)
6. T
22
(non-network transaction)
7. T
36
(network transaction started on \C)
8. T
21
commit
9. T
22
commit