[erlang-questions] MNESIA BACKUP IN LARGE SYSTEMS

Joshua Muzaaya <>
Mon Oct 10 16:24:51 CEST 2011


Thanks guys for supporting us through this forum

In our setup, we found that issuing the following backup call with
mnesia:backup_checkpoint(Name,
Opaque, [Mod]) is more expensive as compared to this one:
(mnesia:backup(Opaque,
[Mod])). The issue is to do with Memory. Whenever we specify our own
checkpoint name, mnesia consumes a lot of memory than when we leave it to do
its thing. By using the later function, we only specify the file name of the
resultant backup and all goes well, But i have a question below:

Backups work very well, however, i wonder, in a system running a replicated
schema (database across 3 Nodes), if i issue a mnesia backup on one of the
Nodes, does the back up only consider the local table state or the backup is
transactional (ATOMIC) in nature in that mnesia may consult involved Nodes
to find all the most recent changes in other replicas in order to make the
back up. In other words, what is the scope of the backup in cases of say:
Fragmentation, Replication, in cases where i have some Nodes down and in
cases where a remote table has more recent data than the one on which the
backup call is issued ?

thanks in advance guys

*Muzaaya Joshua
Systems Engineer
+256774115170*
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