[THIN] Re: Dual ZDCs?
- From: "Joe Shonk" <joe.shonk@xxxxxxxxx>
- To: <thin@xxxxxxxxxxxxx>
- Date: Thu, 4 Dec 2008 07:35:33 -0700
Do these servers have multi-nics connected to different networks? If so,
that is probably where your problem lies. While it is possible to use
multiple NICS (not bonded), it is highly NOT recommended and definitely not
a best practice.
Each zone had a 1 Data Collector (DC) that is elected. So if you have two
zones, you will have two DCs (or we like to call them ZDCs).
Any server that has direct access to the database can function as a DC so in
order to dedicate a server/vm to this role you must set the election
preference (Most Preferred). Some organizations like to have a backup ZDC.
Technically, there is no such thing. It's simply a server that has been
dedicated to serve as the ZDC in the event the real ZDC become unavailable.
Again, this is accomplished by setting election preference so the machine is
next in line. This prevents an application server from becoming the DC in
the event of a failure.
Now having a "backup" ZDC is nice because you can also use that server to
host additional infrastructure services or act as a backup. So in the event
of a failure of an infrastructure server you're not impacting your
application servers. Examples of additional infrastructure services. DC
Role, XML, STA, Metric Server. Smaller farm could also host Web Interface
and the Licensing server (CTX and/or MS) while large orgs will want to split
WI and Licensing onto separate servers.
Also, the imalhc.mdb is the local host cache, not the Data Store. Do you
know if your data store is Access, SQL Express or SQL?
Joe
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf
Of Stephanie Atkinson
Sent: Thursday, December 04, 2008 5:49 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Dual ZDCs?
Hi Jeremy,
Thanks for your suggestions. I checked out a few things yesterday after
speaking with a more senior Admin who has been on vacation. In some ways he
confused me even more trying to tell me that when you build the farm you
designate the zone masters (2 in our case supposedly, when to me it just
seems like a primary of most preferred and a backup of preferred) and that
that info is stored in the imalhc.mdb (copy of persistent, not
non-persistent data) on each server telling it to only communicate with the
ZM in that database. He also explained how the member server communicates
with the ZM via the MGT NIC then the ZM sends the info back on the
client-side NIC thus it's only able to send back to the same member server.
I find flaws with both of these explanations but I think you're right that
the answer to my question lies in our configuration. One thing I did find
is that we don't have ports 2512, 2513 or 1494 open between non ZM servers,
only from member server to ZM. That would seem to account more for the lack
of available info in the CMs.
I started questioning this b/c I am studying for my CCA. The more you learn
the more you can question. Anyhow, I will just keep digging into this.
Thanks for your clarifications.
Best Regards,
Stephanie
Jeremy Saunders <Jeremy.Saunders@xxxxxxxxxxxxxx> wrote:
Hi Stephanie,
Have a look at the way the Presentation Server Administrators have been set
up in the Access Management Console, and perhaps also the DCOM permissions
on the servers, ensuring that the COM Plus network access Windows component
has been added to all servers. As far as I'm concerned, this stuff should
configured the same across all servers. Maybe you need to quiz that Engineer
a bit further???
Cheers,
Jeremy.
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf
Of Stephanie Atkinson
Sent: Wednesday, December 03, 2008 8:23 PM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Dual ZDCs?
I'd forgotten the qfarm identifies the ZM as well. I ran that and it
confirmed just 1 ZM is in affect. So then here is where I guess I am
confused. You stated,
By the way, it is not a requirement to run the Access Management Console or
Presentation Server Console (AKA CMC) from the Data Collector. Any farm
server will do, and if your zone is working correctly, the information
returned will be consistent no matter which server you connect to.
and when I read that ports 2512 and 2513 are used for server to server and
server to MC respectively, I took that to mean that all MCs from all servers
in a given farm provide results for all servers in the farm. In our case, it
is only the dedicated primary and backup ZMs that have this bird's eye view
for Servers. The MCs from any other server DO provide Pub App and Policies
data for example but NOT Servers. So you can't see what users are logged
on, try to shadow or directly connect to any other server than the one you
are logged on to.
Regards,
Stephanie
Jeremy Saunders <Jeremy.Saunders@xxxxxxxxxxxxxx> wrote:
Hi Stephanie,
What you are seeing is correct, it obviously just hasn't been explained to
you correctly. The Engineer should have whiteboarded this for you.
Each zone can only have ONE Data Collector at any one time. You have a
"Primary", which will always be the server set to "Most Preferred", and you
have a Backup, which is set to "Preferred". The backup will take over when
the Primary fails, is taken off-line, etc. I personally always set the
remainder of farm member servers to "Not Preferred" to ensure they never
take part in any zone elections. Others will leave them set to "Default",
just in case.
If you go to the command line on any server, type "qfarm". This will list
all servers in the farm. The ones with the D after their IP Address will be
the active Data Collectors for those zones. So in your case you will see
two.
By the way, it is not a requirement to run the Access Management Console or
Presentation Server Console (AKA CMC) from the Data Collector. Any farm
server will do, and if your zone is working correctly, the information
returned will be consistent no matter which server you connect to.
I hope that explains it.
Cheers,
Jeremy.
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf
Of Stephanie Atkinson
Sent: Wednesday, December 03, 2008 9:58 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Dual ZDCs?
How is it that a Zone can have 2 operating Data Collectors? Of everything I
have read, each zone can only have one so maybe I misunderstand what is
going on. The Citrix Engineer who setup this environment advised we have
data collection on 2 servers because 1 is set to Most Preferred and the
other Preferred. All other servers are left to default. We have 2 dedicated
servers for each zone intended to be data collectors and by all accounts
that is how they are working. All the information from every server in the
zone is available from both servers in the CMC; all other servers only
provide their local information.
Can anyone clarify or explain this?
Thanks,
Stephanie Atkinson
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