The leader doesn't really do a lot more work than any of the replicas, so I don't think it's likely that important. If someone starts running into problems, that's usually when we start looking for solutions.
- Mark On Feb 21, 2013, at 10:20 PM, "Vaillancourt, Tim" <tvaillanco...@ea.com> wrote: > I sent this request to "ServerA" in this case, which became the leader of all > shards. As far as I know you're supposed to issue this call to just one > server as it issues the calls to the other leaders/replicas in the > background, right? > > I am expecting the single collections API call to spread the leaders evenly > across SOLR instances. > > Hopefully I am just doing/expecting something wrong :). > > Tim Vaillancourt > > -----Original Message----- > From: Upayavira [mailto:u...@odoko.co.uk] > Sent: Thursday, February 21, 2013 1:44 PM > To: solr-user@lucene.apache.org > Subject: Re: Is it possible to manually select a shard leader in a running > SolrCloud? > > Which of your three hosts did you point this request at? > > Upayavira > > On Thu, Feb 21, 2013, at 09:13 PM, Vaillancourt, Tim wrote: >> Correction, I used this curl: >> >> curl -v >> 'http://<HOST>:8983/solr/admin/collections?action=CREATE&name=test&numShards=3&replicationFactor=2&maxShardsPerNode=2' >> >> So 3 instances, 3 shards, 2 replicas per shard. ServerA becomes leader >> of all 3 shards in 4.1 with this call. >> >> Tim Vaillancourt >> >> -----Original Message----- >> From: Vaillancourt, Tim [mailto:tvaillanco...@ea.com] >> Sent: Thursday, February 21, 2013 11:27 AM >> To: solr-user@lucene.apache.org; markrmil...@gmail.com >> Subject: RE: Is it possible to manually select a shard leader in a >> running SolrCloud? >> >> Thanks Mark, >> >> The real driver for me wanting to promote a different leader is when I >> create a new Collection via the Collections API across a multi-server >> SolrCloud, the leader of each shard is always the same host, so you're >> right that I'm tackling the wrong problem with this request, although >> it would fix it for me. >> >> If I create the cores manually via the cores API, one-by-one, I am >> able to get what I expect, but when running this Collections API call >> on a 3 SOLR 4.1 instance, 3 shard setup, 1 server becomes the leader >> of all 3 shards, meaning it will get all the writes for everything >> (correct me if I am wrong). If so, this will not scale well with all >> writes to one node (or correct me if I am wrong)? >> >> curl -v >> 'http://<HOST>:8983/solr/admin/collections?action=CREATE&name=test&numShards=3&replicationFactor=1&maxShardsPerNode=2' >> >> Currently on my 3 instance SOLR 4.1 setup, the above call creates the >> following: >> >> - ServerA is the leader of all 3 shards (the problem I want to address). >> - ServerB + ServerC are automagically replicas of the 3 leader shards >> on ServerA. >> >> So again, my issue is one server gets all the writes. Does anyone else >> encounter this? If so, I should spawn a separate thread on my specific >> issue. >> >> Cheers, >> >> Tim >> >> -----Original Message----- >> From: Mark Miller [mailto:markrmil...@gmail.com] >> Sent: Tuesday, February 19, 2013 8:44 PM >> To: solr-user@lucene.apache.org >> Subject: Re: Is it possible to manually select a shard leader in a >> running SolrCloud? >> >> You can't easily do it the way it's implemented in ZooKeeper. We would >> probably internally have to do the same thing - elect a new leader and >> drop him until the one we wanted came up. The main thing doing it >> internally would gain is that you could skip the elected guy from >> becoming the actual leader and just move on to the next candidate. >> Still some tricky corner cases to deal with and such as well. >> >> I think for most things you would use this to solve, there is probably >> an alternate thing that should be addressed. >> >> - Mark >> >> On Mon, Feb 18, 2013 at 4:15 PM, Vaillancourt, Tim >> <tvaillanco...@ea.com> >> wrote: >>> Hey all, >>> >>> I feel having to unload the leader core to force an election is "hacky", >>> and as far as I know would still leave which node becomes the Leader to >>> chance, ie I cannot guarantee "NodeX" becomes Leader 100% in all cases. >>> >>> Also, this imposes additional load temporarily. >>> >>> Is there a way to force the winner of the Election, and if not, is there a >>> known feature-request for this? >>> >>> Cheers, >>> >>> Tim Vaillancourt >>> >>> -----Original Message----- >>> From: Joseph Dale [mailto:joey.d...@gmail.com] >>> Sent: Sunday, February 03, 2013 7:42 AM >>> To: solr-user@lucene.apache.org >>> Subject: Re: Is it possible to manually select a shard leader in a running >>> SolrCloud? >>> >>> With solrclound all cores are collections. The collections API it just a >>> wrapper to call the core api a million times with one command. >>> >>> to >>> /solr/admin/cores?action=CREATE&name=core1&collection=core1&shard=1 >>> >>> Basically your "creating" the shard again, after leader props have gone >>> out. Solr will check ZK and find a core meeting that description, then >>> simply get a copy of the index from the leader of that shard. >>> >>> >>> On Feb 3, 2013, at 10:37 AM, Brett Hoerner <br...@bretthoerner.com> wrote: >>> >>>> What is the inverse I'd use to re-create/load a core on another >>>> machine but make sure it's also "known" to SolrCloud/as a shard? >>>> >>>> >>>> On Sat, Feb 2, 2013 at 4:01 PM, Joseph Dale <joey.d...@gmail.com> wrote: >>>> >>>>> >>>>> To be more clear lets say bob it the leader of core 1. On bob do a >>>>> /admin/cores?action=unload&name=core1. This removes the core/shard >>>>> from bob, giving the other servers a chance to grab leader props. >>>>> >>>>> -Joey >>>>> >>>>> On Feb 2, 2013, at 11:27 AM, Brett Hoerner <br...@bretthoerner.com> wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> I have a 5 server cluster running 1 collection with 20 shards, >>>>> replication >>>>>> factor of 2. >>>>>> >>>>>> Earlier this week I had to do a rolling restart across the >>>>>> cluster, this worked great and the cluster stayed up the whole >>>>>> time. The problem is >>>>> that >>>>>> the last node I restarted is now the leader of 0 shards, and is >>>>>> just holding replicas. >>>>>> >>>>>> I've noticed this node has abnormally high load average, while >>>>>> the other nodes (who have the same number of shards, but more >>>>>> leaders on >>>>>> average) >>>>> are >>>>>> fine. >>>>>> >>>>>> First, I'm wondering if that loud could be related to being a 5x >>>>>> replica and 0x leader? >>>>>> >>>>>> Second, I was wondering if I could somehow flag single shards to >>>>> re-elect a >>>>>> leader (or force a leader) so that I could more evenly distribute >>>>>> how >>>>> many >>>>>> leader shards each physical server has running? >>>>>> >>>>>> Thanks. >>>>> >>>>> >>> >>> >> >> >> >> -- >> - Mark >> >
