TDB mutex support breaks CTDB

[Stefan (metze) Metzmacher]

Am 11.12.2014 um 05:50 schrieb Amitay Isaacs:
> Hi Volker/Metze,
> 
> The TDB robust mutex changes make certain assumptions which completely
> breaks CTDB.  Here are some of the findings which are causing concern.
> 
> 1. CTDB does not always specify all the matching flags (i.e. the flags used
> for creation) to tdb_open_ex() when opening tdb database subsequently (or
> in not-first case).  This does not work for databases created with
> TDB_MUTEX_LOCKING.
> 
> 2. If I specify TDB_MUTEX_LOCKING in tdb_flags for subsequent (non-first)
> tdb_open_ex(), it does not work unless I also include TDB_CLEAR_IF_FIRST.
> If the process knows that it's not the first opener, why should it need to
> specify TDB_CLEAR_IF_FIRST?

As indication that it's a non persistent database.

> 3. CTDB database recovery uses transactions to update the databases after
> recovery.  With TDB_MUTEX_LOCKING enabled, CTDB cannot do database recovery.

Can the all record lock be used instead of a transaction?
I wonder why we didn't notice this before...

> First two issues can be resolved by modifying CTDB to pass correct flags to
> tdb_open_ex().

Please do that.

metze

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