I do love when everyone starts flexing their technical muscles and as was
said earlier it becomes a religious discussion. Reminds of the Notes vs
Exchange conversations or iPhone vs Android....

all those decisions as well as your decision on MImix vs PowerHa or iTera
or QEDD etc. need the requirements of the business. What are you trying to
solve? .

All the solutions have benefits and limitations, suffice it to say, that
getting someone who knows the technologies cold is the key. Whether full
mirror is good, whether Mimix more QEDD then with proper planning, the
biases that you're reading here won't matter.




Augie Palumbo
312-735-3723
702-826-2836


On Fri, Jan 10, 2020 at 7:52 AM DrFranken <midrange@xxxxxxxxxxxx> wrote:

> We're doing mostly replication. One reason: depending on the crash,
> you don't know the state of the SAN
> (if you do full mirror including OS parts).

I Do not like the 'Full OS Mirror' option. I don't. Not even a little.
Don't like it. Not a fan. You might wonder why.

First you lose many of the options that you have with other choices. You
have no ability to use the backup site for anything. You can't do PTFs
on one side while you run on the other side. You can't do backups on one
while you run on the other. You can't do upgrades on one while you run
on the other. Testing on the backup side requires a full stop of
replication and likely a long time to get back in sync.

You guarantee an abnormal IPL absolutely. It may or may not come up
correctly or quickly. It might not come up at all. It also adds
significantly to replication traffic as all temp writes etc are
replicated needlessly.

In summary I don't like it. Yes I have done it and in our tests we found
issue after issue. Replicating iASP only is far better though still not
perfect.


- Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
www.iInTheCloud.com - Commercial IBM i Cloud Hosting.

On 1/10/2020 10:21 AM, Holger Scherer wrote:
This is always some kind of religious question:
- do SAN mirror with two boxes, or
- do replication with MIMIX (or other software. Here in germany BUS4i is
the star replacing Mimix)

We're doing mostly replication. One reason: depending on the crash, you
don't know the state of the SAN
(if you do full mirror including OS parts).
We had one customer whose production system crashed (running about 180TB
database).
The switchover to the backup box with mirrored SAN was fast, but the IPL
with
checking the database, LF etc needed some 12 hours on a not so small box
;-)

-h


Am 10.01.2020 um 15:56 schrieb DrFranken <midrange@xxxxxxxxxxxx>:

Wanna know the best part? The SANs continue replication while you do
the PTFs and / or OS UPgrade!!! So you're not even behind when you're done.
Try THAT with MIMIX and friends!


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