There is no true HA solution that allows you to take a machine out of your network and continue processing
All of the vendors provide replication from a primary machine to a
backup machine. The last real hands on experience and testing I did took
45 minutes to synch up a MIMIX based machine after cutting over to the
backup machine.
Sadly, unlike Linux or Unix you do not have real-time replication or load
balanced system sharing that actually run parallel systems instead of
primary & backup. This has been a huge shortcoming of OS/400 and
IBM i forever. There may have been some improvement, but I've not seen them.
There are some good data replication products for IBM, I like Mimix which
I used. The key to my comments are the fact that this has been an area
of weakness since the AS/400 was first shipped. While Mimix and other
products can provide data replication between machines there is no true
HA solution that allows you to take a machine out of your network and
continue processing as you can with other platforms and OS's.
For many IBM i customers data and object replication can be sufficient
if you thoroughly review your program change management, security
administration, network administration, etc. and make sure that:
1. You do not lose in flight data or that you know what you lose when you cut over.
2. Any programs that have been updated or changed on your primary machine are replicated to your back up machine.
3. Any other resources besides data or programs are replicated and synchronized.
4. User profiles and other security settings are synchronized, and
5. You have a network configuration that allows you to switch users to your backup machine.
This is not trivial and this really sets the vendors apart from each
other. But keep in mind. Unlike modern could based scenarios you
CANNOT balance your work load across multiple IBM i based systems and
simply take one offline and keep on processing. You can do this on
other platforms including Unix, Linux, and Windows.
*Disclosure: I am a real user, and this review is based on my own experience and opinions.
![MIMIX [EOL] Logo](https://images.peerspot.com/image/upload/c_scale,dpr_3.0,f_auto,q_100,w_100/vrgt1zpi8gqi3wy9lt9smu963yx9.jpg)
