Mac OS X 10.3.9 - SID-UID mappings

James Peach jpeach at
Sun Jan 6 06:21:55 GMT 2008

On 05/01/2008, at 4:50 AM, Wolfgang.968 wrote:

> James Peach-3 wrote:
>> On 04/01/2008, at 9:45 AM, Wolfgang.968 wrote:
>> In general, Open Direcotory will generate a SID on the fly using the
>> Samba-style algorithmic RID method. If you need to do better than
>> this, you can store a SMBSID or SMBRID attribute in the user, group  
>> or
>> copmuter record and that will get used instead.
> Ahaaa! That means to me, there is no need to backup any mappings  
> (and it's
> probably not possible at all) as they would be reassigned the same  
> way after
> they get lost after a computer break

You would need to back up your Open Directory data store.

> In my understanding, they would
> even be reassigned to the same values on a different Mac OS X machine?

They should be (unless the machine or domain SID changes). That is  
certainly the intent, though there may be some corner cases where the  
input (Open Directory account records) is ambiguous.

James Peach | jpeach at

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