h.b.furuseth@usit.uio.no wrote:

hyc@symas.com writes:

...

IMO defaulting schemacheck off for replication is fine because replicated entries will have been checked on the master.

What if two simulaneous, valid changes to the same entry on two masters produce a schema error when combined? I haven't been tracking MMR - does the entry end up with a schema error, or does MMR consider two changes to the same entry a conflict and fail to replicate, or...?

AFAIK, the last entryCSN should win. Something like:

MM1 MM2

time 0 csn0 csn0 (same)

time 1 csn0+1 -> -

time 2 - <- csn0+2

time 3 csn0+1,csn0+2 csn0+2,csn0+1 (one wins, I assume the latest)

At all times, each entry is sane. The one that wins is sane, the one that loses will be replaced by the one that wins.

The reason for this ITS and other stuff that will come shortly is that I've been asked to audit MMR, by designing a suite of tests that check functionality and reliability of MMR under possibly reproducible conflict, concurrency and other critical conditions.

I'm highlighting a series of issues. I won't post ITSes or other notices until I find out whether it's slapd's or my tests' fault.

p.

Ing. Pierangelo Masarati OpenLDAP Core Team

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