I looked at SystemMirror multiple times. I even discussed it with IBMers
at the last COMMON.
It has no benefit for me.
This is how I picture SystemMirror working:
- You have BOX1 at location a
- You have BOX2 at location b
- Neither has any physical disk.
- They both use SAN storage.
- This SAN may, or may not, be replicated to another SAN. Depending on
the size of your checkbook.
This may be an acceptable solution if your concerns include:
- Physical damage to BOX1 or BOX2.
- A hardware move of BOX1 or BOX2 to another location.
- A hardware upgrade of BOX1 or BOX2
What it didn't address is what about OS upgrades, ptf installation and
that ilk? The fact that you have redundant boxes but they both rely upon
the same disk makes both boxes out of commission when you are upgrading
the OS on that disk.
A bulk of my planned outages are to install PTF's. Since I had to have an
alternative solution to achieve this with minimal outages of my system I
will use my alternative solution for everything.