Re: Thoughts on this design for Power server installation across two data centers -- MIDRANGE-L

Hi Evan

I think what you're say about IP addresses etc. is okay. For the mainframe
we replicate the entire SYSRES volume and data so when we bring up the DR
LPAR, it looks exactly like production which is what we want. For testing
we create routing rules to stop production traffic reaching the DR box
since it has the same IP addresses as production. In DR that would be fine.

For the Power servers, given it has a number of external connections (to
mainframe and other systems as well as inbound connections), having the
same IP address etc. would be ideal. If production is down, then I want all
network traffic to reach the DR box. We might need some router changes to
enable this but users would be none the wise.

I would imagine IBMi would IPL okay with the same keys as the production
instance. It would not check the licence against the CPU ID would it? As
for ISV software, then we might have to load keys again but that should not
be an issue.

I don't know much about the log shipping products but at the moment the RPO
is not zero for the DR instance and I want to make it zero. SAN replication
should do that (sites about 50 km's apart).

On Sat, Dec 14, 2019 at 9:11 AM Evan Harris <auctionitis@xxxxxxxxx> wrote:

Hi Laurence

if you do SAN replication only then what you have in your other data centre
is an exact copy of production, including such things as IP addresses, host
names, Product License keys (possibly serial number based) etc. If you use
PowerHA or one of the log shipping products (Mimix, QuickEDD et ) they
allow you to maintain separation between these things by excluding certain
files/libraries (log-shipping) or keeping them in separate disk pools
(PowerHA uses IASPs to control the replicated data) I am glossing over a
lot of details here.

To reference your comment about why you can't bring the system up using SAN
replication, remember that the IBM i uses single level storage so that you
don't actually have an isolated boot disk; the whole system is one
contiguous storage space. When the system is started on a SAN copy after an
abnormal failure it will go through an extended database recovery to ensure
the system is consistent,so you need to be prepared for that in terms of
your RTO. If you plan the failover and shut the source down nicely then the
database (aka pretty much the whole system) will be in a consistent state
at the other end and your system and will start up fine - but as I said
earlier it will have the same serial number, TCP IP address and other
system attributes as the original system. This may or may not be a problem
for you especially if you have taken it into account.

If this will work for you and given the amount of data your are talking
about IBM VM restart technology product (formerly GDR) might be enough to
meet your needs.

On Fri, Dec 13, 2019 at 10:42 PM Laurence Chiu <lchiu7@xxxxxxxxx> wrote:

I did answer in another thread. The point of LTO tapes was to take

offsite

backups in a another city. So while I realise that replicate between two
VTL's does mean there is an offsite copy, for our archiving purposes it's
not enough.

Interesting point about Mimix. If I plan to do SAN to SAN mirroring

(using

say an IBM V5020) then why do I need software to mirror also? We did get

a

quote for Mimix and it exceed the cost the SAN's! I have never heard of
Quick-EDD but will check it out.

For encryption I was thinking of using SKLM which we use to encrypt the
data on our DS8886's. Those servers are not accessible externally so are
well protected from ransomware (I hope!)

On Fri, Dec 13, 2019 at 1:18 AM Rob Berendt <rob@xxxxxxxxx> wrote:

Why physical LTO7 tapes? We use two VTL's which replicate from one DC

to

the other. I easily take a backup performed on a system at one DC and
restore it on the system at the other DC.
We use BRMS and it does a dandy job.
We used to use BRMS with physical tapes and that did a fine job of
tracking where the tapes were, preparing the case to send to Iron

Mountain,

receiving tapes back in, etc. But, really, only using VTL saved a LOT

of

manpower. There was one time, (pre VTL) we needed a rush tape back

from

Iron Mountain. They buggered up the job and delivered it to the wrong
building in our complex. The building was owned by a totally different
company. Took awhile to straighten out that mess. Strong argument for
tape encryption though.

About the only argument for retaining physical media I've heard is the
case of ransomeware hitting your VTL's. Then again, if you're

encrypting

your tapes you'd better make sure your keystore is ransomware proof.

We have no physical tapes, and no physical tape drives left. None.
I've done bare metal restores to new systems using the VTL's.

For system to system replication we were using Mimix but switched to
Quick-EDD.

Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1
Group Dekko
Dept 1600
Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com

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Regards
Evan Harris
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