Hello!

Could you please give me an explaination of what is Consistency group (CTG) in Hitachi and how exactly it works?

Thanks.......

:-)

A consistency group guarantees in order delivery of packets from devices within each group.  This allows the remote disk subsystem to apply deltas in order when packets arrive in a different order than they were sent.  Does that answer your question?

Thanks Snig.........

just wanting to know in bit more detail, what is it exactly that helps maintaining this consistency and how????

Thanks & regards.......

In the mainframe world HDS uses time stamps to keep track of packets in flight and applies them in order on the remote side.

In the open systems world HDS uses simple markers to do the same thing.  Since there is no central clock on all open systems servers, they can't really use the time stamps.

Thanks for your reply Snig :-)

No problem buddy.  Now let's get some more discussion going here...