On Aug 27, 2013, at 11:54 AM, Erick Erickson <erickerick...@gmail.com> wrote:
> Soft commits flush to the op system, so > a JVM crash/termination shouldn't affect it anyway. A soft commit is not a hard commit, so there are not guarantees like this. It searches committed and non committed segments - non committed segments will not magically be committed after a JVM crash. > Turning on the fsync > would just be a little bit of extra protection…. If you don't have replication, it turns on strong 'durability' promises. Without it, you are on your own if you have a hard machine reset. If durability is important to you and you don't have replication, it's important to use the fync option here. Unless you have a great, long time, battery backup and/or an env such that hard resets don't concern you for some reason. It comes down to your requirments. Responses to Sandro inline below: On Aug 27, 2013, at 11:43 AM, Sandro Zbinden <zbin...@imagic.ch> wrote: > Hey Mark > > Thank you very much for the quick answer. We have a single node environment. > > I try to find the fsync option but was not successful. Ended up in the > UpdateLog class :-) > > How do I enable fsync in the solrconfig.xml ? In the updateLog config, its a syncLevel=fsync param. > > > Besides that: > > If solr soft commit feature has a on disk guarantee with a transaction log > why we don't use solr soft commit as the default commit option ? Yes, for visibility you should use soft commit. You should also have an auto hard commit with openSearcher=false - it's just about flushing the transaction log and freeing memory in this configuraiton - which is why it makes sense to simply turn on the auto commit for regular hard commits. You may or may not want to use auto soft commits. - Mark > > > -----Ursprüngliche Nachricht----- > Von: Mark Miller [mailto:markrmil...@gmail.com] > Gesendet: Dienstag, 27. August 2013 17:12 > An: solr-user@lucene.apache.org > Betreff: Re: Transaction log "on-disk" guarantees > > > On Aug 27, 2013, at 11:08 AM, Sandro Zbinden <zbin...@imagic.ch> wrote: > >> Can we activate the transaction log to have on disk guarantees and then use >> the solr soft commit feature ? > > Yes you can. If you only have a single node (no replication), you probably > want to turn on fsync via the config. > > - Mark >
