Re: (ITS#5661) contextCSN gets corrupted on the stand by mirror

[ando@sys-net.it]

Ali Pouya wrote:
> Hi Pierangelo,
>>> contextCSN: 20080727021429.070493Z#000000#000#000000
>>> contextCSN:: +HYDCTA4MDIwMzM3MTguMzAwMTExWiMwMDAwMDAjMDAxIzAwMDAwMA==
>>
>> which looks like
>>
>> 4 bytes of garbage + "0802033718.300111Z#000000#001#000000"
>>
> Yes, but I would like to bring a precision :
> under VI the 4 bytes are handled as 2 characters only.

That's probably because vi incorrectly interprets that as a multi-byte 
encoding, since it contains garbage.  That's supposed to be a string 
restricted to those chars that are allowed by generalized time, so you 
shouldn't rely on vi guesses based on their actual, erroneous content.

> In fact each time 
> the problem occurs I repair my database using a BDB C program wich reads 
> the first key from id2entry.bdb and writes it on disk.
> Then I use vi to fix the contextCSN, before writing the key back to the 
> database.
> Using vi I do not delete any characters. I only replace them by 20, then 
> I fix the rest of the fields.

Then you'd get year 20 AD!  The 08 you see in your broken entryCSN is 
the month, not the last two digits of the year.

> Another precision : when the first two chars take corrupted, the rest of 
> the contextCSN gets stuck and does not follow write operations.
> 
>> I note that, according to the sid values you assigned to servers A and 
>> B, the first contextCSN should not appear, since it has sid == 0, 
>> while the second one, apart from the corruption, is plausible (as 
>> you're writing to server A, with sid == 1).
>>
> Yes.
> The contextCSN with sid=0 is there because at the beginning I initiated 
> my directory without SID (defaults to 0), then I set two difrent SIDs 
> for A and B.

Can you try a fresh reload of the database(s) stripping out the entryCSN 
and letting slapadd generate them, using the -S <SID> switch (along with 
the -w switch), in order to enforce a SID of 001 (or 002, as you like)?

p.


Ing. Pierangelo Masarati
OpenLDAP Core Team

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