Archived from groups: microsoft.public.win2000.active_directory (
More info?)
<harsh_bapat@persistent.co.in> wrote in message
news:1117442635.716186.292550@f14g2000cwb.googlegroups.com...
> Hi,
>
> Microsoft describes a mechanism "Polling for Changes Using USNChanged"
> for AD.
>
http://msdn.microsoft.com/library/default.asp?url=/libr...
>
> I am wondering if this mechanism holds true for a Global Catalog
> scenario. I am new to the Global Catalog concept. From what I
> understand, GCs host a copy of every partition in the forest
Not exactly.
> (a full
> copy of their own domain's domain partition, a full copy of the schema
> partition, a full copy of the configuration partition,
The above is just a DC and as a DC the GC starts with these
in any case.
> and a read-only
> copy of every other domain's domain partition with only a subset of
> attributes for each object),
The key distinction here is that it is a subset or PARTIAL
copy of the other Domain partitions -- only a limited amount
of info is copied for every object in the forest.
> then an object addition/modification to
> any domain will cause replication to all DCs in that domain, as well as
> to all GCs, whether or not they are DCs for that domain.
Sort of -- an addition will cause replication to the GCs, but a
modification may or may not depending on whether the property
modified is among the subset held on each GC.
GCs setup a similar (parallel) replication topology, just as
regular DCs do -- they will replicate those additional partial
domain partitions across the domain boundaries (forest wide.)
GCs use the same mechanisms to do this as do ordinary DCs
for domain replication.
Of course the GC cannot write to the domain partition from
domains other than its own -- this is precisely analogous to
every DC having a read only copy of the schema but replicating
it.
> Attributes
> uSNChanged and uSNCreated are available in GC as read-only attributes.
>
(
http://msdn.microsoft.com/library/default.asp?url=/libr...
dschema/a_usnchanged.asp).
> Definition of 'uSNChanged' says - USN value assigned by the *local
> directory* for the latest change, including creation. So at local AD
> level 'uSNChanged' value is unique for each change. I am wondering how
> this is taken care at GC level as it is maintainaing 'uSNChanged' from
> various *local* ADs? i.e. How changes are tracked at Global Catalog
> level? Any ideas?
Just like ordinary partitions, but it isn't a very important concern
unless you have a specific (likely a 'bug') problem....
--
Herb Martin, MCSE, MVP
Accelerated MCSE
http://www.LearnQuick.Com
[phone number on web site]