One of our customers wishes to upgrade their mvBase server to two
identical servers and replicate the mvBase and other data on the
primary server to the standby server in real time using a Windows O.S.
level replication tool like DoubleTalk or Legato Replistor
(asynchronous) or Legato AutoStart (synchronous).

Does anyone have any thoughts or experience with this sort of
replication?

Thanks,

Dave

Just some stray thoughts ... we considered similar products years ago
for D3/NT

Issues we ran into included data being stored in RAM "for a while",
reducing the "realtime" value, and also having some files "updated" and
others not. At the time (>5 years ago) the product we were looked at
(for under a day) had no knowledge of D3, so if you changed 20 bytes in
a record, it faithfully went & replicated another copy of the 300Mb
file .... so make sure that the product can cater for such
"incremental" changes in a "timely" manner




davet (AT) sysmarkinfo (DOT) com wrote:

Dave, I think you'll find the problems described by Ross will change
your approach. There are blob issues as well as referential integrity
issues when trying to capture "atomic" data from an MV environment.
With D3 at least we have triggers which can write data to the host OS
or to other environments. You don't have this luxury with mvBASE.

(Can someone check me on that? Is it correct that there is still no
trigger handling in mvBASE v2? Any plans for it?)

If your client doesn't mind making some changes to their app code, we
can write a trigger interface for mvBASE using mv.NET that will allow
data propagation across servers (even to remote networks). Really
this could pump updates from any MV environment into any other, even
into relational databases, and could serve as a migration tool, but
let's not get ahead of ourselves... Let me know if they'll authorize
effort for a prototype.

HTH
Tony
TG@ removethisNebula-RnD.com

"Ross Ferris" wrote:

As Tony has suggested, the lack of triggers is "a bummer" in terms of a
"roll your own" approach - D3 offers "native" replication, and we also
have a "home grown" solution that allows us to replicate changes to
multiple "mirrors"

If you were willing to CHANGE YOUR APPLICATION (which may be the only
viable solution you have available!) then you may be able to "cheat".
You may find that the changes are quite simple and can be
semi-automated.

Essentially everywhere you write/delete a record, write a corresponding
record out to the OS in a known format ... maybe

what*filename*auditid*realID

where "What" would be (d)elete or (w)rite, filename is (hopefully)
obvious, "auditid" is a unique number/code (see seperate thread), and
the realID is self evident (?)...

Now your challenge is simply to move these files in a known/constant
directory across to the target machine(s) [we have a Visage component
that can be deployed to do this] - it is a fairly simple matter to then
have a phantom process continually scan this directory on the other end
& replicate the deletes/writes.

OR ..... you could always see about a D3 migration ...?

I've never seen an OS level product work correctly with mv files.
I have seen grown men cry out in frustration.

If you try to make it work...put away anything that you treasure that is
breakable, stay away from loved ones, and when it comes time to pull out
your hair try to remember that you HAVE thought of everything.

If you make it work, please let me know. I would love to read all about it.
Even if you have to write in crayon.


<davet (AT) sysmarkinfo (DOT) com> wrote

Albino Timberwolf wrote:

ROFL

--
Kevin Powick

Hi,

I am searching the same solution but can't find any suitable software
can do the job.. >.<


Rgds,

We encountered a bunch of these situations when we were designing and
writing our replucation driver, the UDH.

It's essentially a trigger; any ACD action on the data is repliacted
to mmirrored files on the secondary server. SO, we effectively to
record-level updates.

We also can go into journalling mode so that the mirror can be backed
up in a 'known' state.

fwiw

mike

On Mon, 23 Oct 2006 16:33:15 -0700, Tony Gravagno
<g6q3x9lu53001 (AT) sneakemail (DOT) com.invalid> wrote:

As noted above, if you are on D3/NT you can "easily" roll your own
(with D3/Linux a facility comes out of the box)

If there are enough people interested on the NT platform may have to
look at tidying up our routines & slapping a "Visage" label on them to
take to market :-)


skypirate wrote:

Thanks Kevin. I'm glad you see the humor.

This started as a search for a Windows OS level software search.

I know there are a lot of mv programming solutions. Application updates to
transfer data with a phantom, triggers, etc. There is a long list. These
aren't Windows OS level solutions. Attempting to back up live files is
enough of a problem with most OTS software. Keeping a spare server up to
date with live data? Hmmm.

How many server clusters have you seen in the mv world?

"Kevin Powick" <kevin (AT) powick (DOT) ca> wrote