Windows Server - downgrade schema

Asked By Marce

27-Feb-09 04:28 AM

Hello,

I would like to downgrade the schema version 44 to 31. Is it possible? How
can I do that?

Thanks

Marcel

01-Mar-09 07:02 AM

Marcel,


Not possible. You can't undo Schema changes. Why would you want that?

Cheers,
Florian
--
Microsoft MVP - Group Policy
eMail: prename [at] frickelsoft [dot] net.
blog: http://www.frickelsoft.net/blog.
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27-Feb-09 10:09 AM

Hi Rajesh,

thank for your help. I changed the schema version 44 to 31 in the test
environment at first.

Thanks

Marcel

02-Mar-09 05:21 AM

Hello Marcel,

As Florian stated, it is not possible. Just with changing the number in the
registry you have not changed the schema itself.

Best regards

Meinolf Weber
Disclaimer: This posting is provided "AS IS" with no warranties, and confers
no rights.
** Please do NOT email, only reply to Newsgroups
** HELP us help YOU!!! http://www.blakjak.demon.co.uk/mul_crss.htm

27-Feb-09 10:58 AM

Hi Rajesh,

I' m a little bit confused. I chached it in the registry and reboot my
server. Now I can see the following entries in the registry
Schema Version                REG_DWORD    0x0000002c(44)
System Schema Version    REG_DWORD     0x000001f(31)

thanks

Marcel

28-Feb-09 02:22 PM

windows server 2008 has schema verison 44 and server 2003 has 30
which server edition has schema version 31 ?

as far dwongrade is concerned i belive that is not possible
schema changes are irreversible
please call microsoft PSS for details
you can obtain numbers from
http://www.suppoprt.microsoft.com

27-Feb-09 07:26 AM

Hi Marcel,

By rigistry you can change the vertion of schema.

Note do It in server which is having Schema master Role.


You can verify the operating system support level of the schema by looking
at the value of the Schema Version registry subkey on a domain controller.
You can find this subkey in the following location:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NTDS\Parameters
You can also verify the operating system support level of the schema by
using the Adsiedit.exe utility or the Ldp.exe utility to view the
objectVersion attribute in the properties of the
cn=schema,cn=configuration,dc=<domain> partition. The value of the Schema
Version registry subkey and the objectVersion attribute are in decimal.

Schema Version ObjectVersion values and corresponding operating system
support level
13=Microsoft Windows 2000
30=Original release version of Microsoft Windows Server 2003 and Microsoft
Windows Server 2003 Service Pack 1 (SP1)
31=Microsoft Windows Server 2003 R2


I hope that the information above helps you.
Have a Nice day.

Rajesh J S
MCSA, MCP




Back to the top

01-Mar-09 05:42 AM

Hi,

the server edition "Windows 2003 R2" has the schema version 31.

thanks

Marcel

01-Mar-09 05:51 AM

ok
you extended schema from 31 to 44 using the   adprep /forestprep switch
this command imports files  schema32.ldf to schema 44.ldf to  the SCHEMA
PARTITION
and changes made to the schema partition are irreversible
so it not possible to go back to schema  version 31
so i doubt what you want i achiveable
merely changing the registery or the ObjectVersion attribute is not
scuufficient
plese get in touch wiht MS PSS

01-Mar-09 05:20 PM

Hi
I’ll disagree with everyone else and say that is possible.
How?  The easy way (No I’m not go to refer the hard way :)):

-You need to have a valid backup (valid means that the backup is within your
Tombstone Lifetime. I know there’re other ways to turn around that question,
but let’s stay with the defaults :)), pick the DC for that Backup (or you
can try to apply it to a different hardware, but that may be harder).
-Remove that DC from AD (You can do it manually or using dcpromo, is up to
you- of course make sure that none is dependent of that DC before removing
it).
-Move that DC to an isolated network.
-Perform an full authoritative restore of AD DB, before that you can format
the DC, or do the restore in place for that DC without formatting it.
-Manually remove all DCs that belonged to that AD at that Time. Test the DC
and make sure that everything is OK. Assuming yes, now you’ve the AD schema
version that you want.
-Now you can introduce that DC in the prod network, but first you need to
REMOVE all others.  Additionally the existing Computers and apps must be
“re-pointed” under their DNS/WINS settings to the new DC assuming that the
DC is also a DNS server and/or WINS. If not, you can clean all references in
DNS/WINS and re-register them on those servers.
-The PROBLEMS that you might have (almost certainly). MANY Problems… For
example computer broken security channels, Apps that were introduced after
the schema upgrade and need the missing schema updates. Those are some that
you might face after that operation.
-If you ever consider this… BE AWARE THAT YOU SHOULD PLAN AND TEST IT
CAREFULLY BEFORE IMPLEMENTING IT.
--

I hope that the information above helps you.
Have a Nice day.

Jorge Silva
MVP Directory Services

02-Mar-09 01:54 AM

Howdie!



Is that considered a supported way?

Depending on "how old" that backup is, you don't want to re-apply a
backup that's a month old to a prod environment to "lose" all data that
has been created/changed since then.

Only because you can do it "somehow" by some means (removing all but one
DC) doesn't mean you should do it. I guess I'll stick with the "isn't
possible" statement and save people from messing with their prod
environment. Demoting all but one DC and messing with the one left isn't
something I would suggest a customer - nor anyone on this list here.

Cheers,
Florian
--
Microsoft MVP - Group Policy
eMail: prename [at] frickelsoft [dot] net.
blog: http://www.frickelsoft.net/blog.
Maillist (german): http://frickelsoft.net/cms/index.php?page=mailingliste

02-Mar-09 02:53 AM

Thanks

Marcel

02-Mar-09 02:25 PM

Hi Florian
- It's a normal restore process why it shouldn't be supported.
- Backups are used to restore things. The window time that you define to
have a valid backup is planned before doing those backups. Some companies
can't afford to have VALID backups older than 1hour (of course that will
depend on the technology that you're talking about) others can afford
backups that are older than one month a year, whatever... Do you know when
the poster did the last backup? Or when he did the schema upgrade? An if he
has a very recent backup?
-Before you do schema upgrades is supposed to do a backup first so you can
rollback that action. If you planned carefully that schema upgrade, that
action will only affect one DC at the time, and you can rollback those
actions easily without causing too much down time. However that's not the
point.
- So when you say that IS NOT POSSIBLE YOU'RE WRONG. If you're read
carefully the post that I did you would see that I say that those actions
should be tested and is up to the poster to decide if it is worth the
trouble it's not up to you to decide. When I said that He/ or /She can be
left with only one DC at the worse situation, that doesn't mean that the
poster has to be left with only one DC, in fact I stated that scenario
because (without knowing the real environment where the poster is at) that
can be a reality and, OF COURSE that would be very bad, and the person would
had to think twice before ever consider that as an option. I'm sorry that
you didn't saw that. Is funny that when someone asks what to do before a
schema upgrade or any other upgrade, everyone answers DO BACKUPs do BACKUPs…
But then you CANT use them??
- Is it possible? YES it is.
- Does it worth the trouble? That will depend of many other things like
downtime, affected DCs at this moment, when that upgrade was done, etc...
etc...

--
I hope that the information above helps you.
Have a Nice day.

Jorge Silva
MVP Directory Services

06-Mar-09 02:20 PM

You can't change the schema, you can disbale the attributes if you would
like.  But once added they will always be there.

--
Paul Bergson
MVP - Directory Services
MCTS, MCT, MCSE, MCSA, Security+, BS CSci
2008, 2003, 2000 (Early Achiever), NT4

http://www.pbbergs.com

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