[THIN] Re: Datastore Migration in Large XP Farm
- From: "cherie.watts Watts" <cherie.watts@xxxxxxxxx>
- To: thin@xxxxxxxxxxxxx
- Date: Mon, 15 Aug 2005 10:53:31 +1000
Hi Jeff
Thanks for the information. But from the questions you are asking, I
mustn't have been clear in mine.
I am NOT creating a new Farm.
And the whole "no downtime" is only the case if your servers are in a
N + 1 situation in every published application. Which we don't have.
The situation is the One farm will have 2 identical Datastores
connected to different servers within the farm for a period of 4 days.
Now from all I have read(which may not be enough), Load Balancing is
performed by the Data Collectors on the values that the servers
provide.
The servers calculate their loads based on the Load Evaluators as
designated in the Datastore.
Servers talk to the Datastore every 30mins(defaultly post FR3) to
determine if any changes were made since the LHC was last updated, or
in the event a change has been made to the datastore or ofcourse when
the servers are started(unless you have the DCNChangePollingInterval
registry key set).
So if there are no changes to the Datastore and the datastores are identical!!
Ultimately Load Balancing works just fine if the Datastore is offline
(for 96 hrs anyway).
Theoretically this should work OK. But I will be testing in the Test
Lab over the next few days.
Oh to answer the question as to why I can't do it in the one day. The
business won't allow it.
Thanks
Cherie
On 8/13/05, Jeff Pitsch <jepitsch@xxxxxxxxx> wrote:
> I would also suggest reading the farm maintenance guide at
> http://support.citrix.com. It tells you how to migrate the datastore.
> It is fast, simple, and can be done during production hours without
> any down time.
>
> Jeff Pitsch
>
> On 8/12/05, Jeff Pitsch <jepitsch@xxxxxxxxx> wrote:
> > 1) Load balancing will not work because you can't load balance across
> > farms. What you are proposing is creating a brand new farm. It
> > simply won't work.
> >
> > 2) Again, new farm. No load balancing.
> >
> > You are also goingto have to manually point your clients to the new
> > farm. Hopefully your using Web Interface because otherwise, your in
> > for a lot of pain with your plan. A whole lot of pain.
> >
> > Jeff Pitsch
> >
> > On 8/11/05, cherie.watts Watts <cherie.watts@xxxxxxxxx> wrote:
> > > Hi Guys
> > >
> > > I would really appreciate any feedback on the following scenario.
> > >
> > > We are moving our Datastore to a faster Oracle server.
> > > The farm is Metaframe XP FR2/FR3 on windows 2000/2003 servers. There
> > > are 5 zones with multiple application silos, some silos cross zones.
> > > Some servers are located in datacentres others are remote.
> > >
> > > Now generally I would think that most people would simply export and
> > > import the database onto the new platform and run the dsmaint(with new
> > > dsn file) on the servers to point them to the new database, all on the
> > > weekend and jobs done.
> > >
> > > But our business won't allow us to do this so are looking at doing it
> > > over 4-5 day period. Because of the time delay it's raised a couple of
> > > questions.
> > >
> > > Firstly I can tell you that for the period of time, no changes will be
> > > allowed in the farm until all servers are connecting to the one
> > > database.
> > >
> > > What is the best approach
> > >
> > > 1. Migrate 1-4 application silos each day over a 4 day period. Leave
> > > the Zone Data Collectors to last.
> > > a) Questions I have with this are: Will load balancing still work
> > > correctly if the ZDC's are connecting to the old Datastore, while the
> > > application servers are connected to the new datastore.
> > > b) Will load balancing work correctly for the application silos spread
> > > across Zones.
> > >
> > > 2. Migrate the application silos gradually over the 4 days to the new
> > > datastore. Leave the ZDC's to last
> > > a) Will load balancing work correctly with the application silos
> > > spread across the old and new datastores.
> > >
> > > Theoretically I think both of these should work. Load Balancing info
> > > is all dynamic and stored the ZDC's. As long as the information in
> > > Datastores isn't changed then it should be happy days.
> > >
> > > But servers do check the Datastores every 30mins for updates, what
> > > will the datastores do if a server doesn't check in?
> > >
> > > Any feedback is appreciated. I will ofcourse be running these tests in
> > > the test lab.
> > >
> > > Cheers
> > >
> > > Cherie
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