RE: remote journal

[PaulMmn <PaulMmn@xxxxxxxxxxxxx>]

Jim--

Even with Mimix, a cutover to the backup system is not instantaneous; 
it is not a dual server solution.

Issues include--

-Waiting for the last transactions on the receiving system to be 
applied.  This should only be a few minutes, but it all depends on 
whether the receiving system was behind on the applies or not.

-Switching communications to the alternate machine.  Your router 
should be able to help, but you need to define the conditions that 
define a 'disaster,' so the cutover doesn't happen when you're not 
expecting it.

-Is the cutover automatic, or under manual control.

-Unless you have committment control of your applications, batch jobs 
will not roll back to a known-clean position.

-Interactive jobs will have to connect to the alternate machine and re-start.

Because of the need to have everything under committment control, we 
accept that a calamity that befalls our main system will require some 
time until the backup machine can take over.

We use Mimix mainly to keep a duplicate copy of our data base.  Our 
backups run mostly from the duplicate copy; the users aren't 
disturbed by us needing to save their files.

Our second machine also gives us a playground for programmers; we can 
restrict access to the live system.

--Paul E Musselman
PaulMmn@xxxxxxxxxxxxxxxxxxxx