On Mon, Oct 4, 2010 at 4:58 PM, Upayavira <u...@odoko.co.uk> wrote: > On Mon, 2010-10-04 at 00:25 +0530, Arunkumar Ayyavu wrote: >> I'm looking at setting up multiple masters for redundancy (for index >> updates). I found the thread in this link >> (http://www.lucidimagination.com/search/document/68ac303ce8425506/multiple_masters_solr_replication_1_4) >> discussed this subject more than a year back. Does Solr support such >> configuration today? > > Solr does not support master/master replication. When you commit > documents to SOLR, it adds a segment to the underlying Lucene index. > Replication then syncs that segment to your slaves. To do master/master > replication, you would have to pull changes from each master, then merge > those changed segments into a single updated index. This is more complex > than what is happening in the current Solr replication (which is not > much more than an rsync of the index files). > > Note, if you commit your changes to two masters, you cannot switch a > slave between them, as it is unlikely that the two masters will have > matching index files. If you did so, you would probably trigger a pull > of the entire index across the network, which (while it would likely > work) would not be the most efficient action. > > What you can do is think cleverly about how you organise your > master/slave setup. E.g. have a slave that doesn't get queried, but > exists to take over the role of the master in case it fails. The index > on a slave is the same as that in a master, and can immediately take on > the role of the master (receiving commits), and upon failure of your > master, you could point your other slaves at this new master, and things > should just carry on as before. Wouldn't this require restart of Solr instances?
Sorry, I couldn't respond to you earlier as I wasn't checking my mails for sometime. > > Also, if you have a lot of slaves (such that they are placing too big a > load on your master), insert intermediate hosts that are both slaves off > the master, and masters to your query slaves. That way, you could have, > say, two boxes slaving off the master, then 20 or 30 slaving off them. > >> And does Solr support replication between masters? Otherwise, I'll >> have to post the updates to all masters to keep the indexes of masters >> in sync. Does SolrCloud address this case? (Please note it is too >> early for me to read about SolrCloud as I'm still learning Solr) > > I don't believe SolrCloud is aiming to support master/master > replication. > > HTH > > Upayavira > > > -- Arun
