bq: I read somewhere that you should run your own ZK externally, and
turn off SolrCloud
this is a bit confused. "turn off SolrCloud" has nothing to do with
running ZK internally or externally. SolrCloud requires ZK, whether
internal or external is irrelevant to the term SolrCloud.
On to running an external ZK ensemble. Mostly, that's administratively
by far the safest. If you're running the embedded ZK, then the ZK
instances are tied to your Solr instance. Now if, for any reason, your
Solr nodes hosting ZK go down, you lose ZK quorum, can't index.
etc....
Now consider a cluster with, say, 100 Solr nodes. Not talking replicas
in a collection here, I'm talking 100 physical machines. BTW, this is
not even close to the largest ones I'm aware of. Which three (for
example) are running ZK? If I want to upgrade Solr I better make
really sure not to upgrade to of the Solr instances running ZK at once
if I want my cluster to keep going....
And, ZK is sensitive to system resources. So putting ZK on a Solr node
then hosing, say, updates to my Solr cluster can cause ZK to be
starved for resources.
This is one of those deals where _functionally_, it's OK to run
embedded ZK, but administratively it's suspect.
Best,
Erick
On Tue, Apr 25, 2017 at 10:49 AM, Rick Leir <rl...@leirtech.com> wrote:
All,
I read somewhere that you should run your own ZK externally, and turn
off SolrCloud. Comments please!
Rick
On April 25, 2017 1:33:31 PM EDT, "Otis Gospodnetić" <
otis.gospodne...@gmail.com> wrote:
This is interesting - that ZK is seen as adding so much complexity
that
it
turns people off!
If you think about it, Elasticsearch users have no choice -- except
their
"ZK" is built-in, hidden, so one doesn't have to think about it, at
least
not initially.
I think I saw mentions (maybe on user or dev MLs or JIRA) about
potentially, in the future, there only being SolrCloud mode (and
dropping
SolrCloud name in favour of Solr). If the above comment from Charlie
about
complexity is really true for Solr users, and if that's the reason
why
we
see so few people running SolrCloud today, perhaps that's a good
signal
for
Solr development/priorities in terms of ZK
hiding/automating/embedding/something...
Otis
--
Monitoring - Log Management - Alerting - Anomaly Detection
Solr & Elasticsearch Consulting Support Training -
http://sematext.com/
On Tue, Apr 25, 2017 at 4:50 AM, Charlie Hull <char...@flax.co.uk>
wrote:
On 24/04/2017 15:58, Otis Gospodnetić wrote:
Hi,
I'm really really surprised here. Back in 2013 we did a poll to
see
how
people were running Master-Slave (4.x back then) and SolrCloud
was a
bit
more popular than Master-Slave:
https://sematext.com/blog/2013/02/25/poll-solr-cloud-or-not/
Here is a fresh new poll with pretty much the same question -
How do
you
run your Solr?
<https://twitter.com/sematext/status/854927627748036608> -
and guess what? SolrCloud is *not* at all a lot more prevalent
than
Master-Slave.
We definitely see a lot more SolrCloud used by Sematext Solr
consulting/support customers, so I'm a bit surprised by the results
of
this
poll so far.
I'm not particularly surprised. We regularly see clients either with
single nodes or elderly versions of Solr (or even Lucene). Zookeeper
is
still seen as a bit of a black art. Once you move from 'how do I run
a
search engine' to 'how do I manage a cluster of servers with scaling
for
performance/resilience/failover' you're looking at a completely new
set
of skills and challenges, which I think puts many people off.
Charlie
Is anyone else surprised by this? See
https://twitter.com/sematext/
status/854927627748036608
Thanks,
Otis
--
Monitoring - Log Management - Alerting - Anomaly Detection
Solr & Elasticsearch Consulting Support Training -
http://sematext.com/
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