Hi, yes a post-optimise copy takes 45 minutes at present. Disk IO is
definitely the bottleneck, you're right -- iostat was showing 100%
utilisation for the 5 hours it took to optimise yesterday...
The master and slave are on the same disk, and it's definitely on my
list to fix that, but the searcher is so lightly loaded compared to
the indexer that I don't think it will win us too much.
As there has been another optimise time question on the list today
could I request that the "10 minute" claim is taken of the
CollectionDistribution wiki page? It's extremely misleading for
newcomers who don't necessarily realise an optimise entails reading
and writing the whole index, and that optimise time is going to be at
least O(n)
James
On 28 Feb 2008, at 09:07, Walter Underwood wrote:
Have you timed how long it takes to copy the index files? Optimizing
can never be faster than that, since it must read every byte and write
a whole new set. Disc speed may be your bottleneck.
You could also look at disc access rates in a monitoring tool.
Is there read contention between the master and slave for the same
disc?
wunder
On 2/27/08 7:08 PM, "James Brady" <[EMAIL PROTECTED]> wrote:
Hi all,
Our current setup is a master and slave pair on a single machine,
with an index size of ~50GB.
Query and update times are still respectable, but commits are taking
~20% of time on the master, while our daily index optimise can up to
4 hours...
Here's the most relevant part of solrconfig.xml:
<useCompoundFile>true</useCompoundFile>
<mergeFactor>10</mergeFactor>
<maxBufferedDocs>1000</maxBufferedDocs>
<maxMergeDocs>10000</maxMergeDocs>
<maxFieldLength>10000</maxFieldLength>
I've given both master and slave 2.5GB of RAM.
Does an index optimise read and re-write the whole thing? If so,
taking about 4 hours is pretty good! However, the documentation here:
http://wiki.apache.org/solr/CollectionDistribution?highlight=%28ten
+minutes%29#head-cf174eea2524ae45171a8486a13eea8b6f511f8b
states "Optimizations can take nearly ten minutes to run..." which
leads me to think that we've grossly misconfigured something...
Firstly, we would obviously love any way to reduce this optimise time
- I have yet to experiment extensively with the settings above, and
optimise frequency, but some general guidance would be great.
Secondly, this index size is increasing monotonously over time and as
we acquire new users. We need to take action to ensure we can scale
in the future. The approach we're favouring at the moment is
horizontal partitioning of indices by user id as our data suits this
scheme well. A given index would hold the indexed data for n users,
where n would probably be between 1 and 100 users, and we will have
multiple indices per search server.
Running server per index is impractical, especially for a small n, so
is a sinlge Solr instance capable of managing multiple searchers and
writers in this way? Following on from that, does anyone know of
limiting factors in Solr or Lucene that would influence our decision
on the value of n - the number of users per index?
Thanks!
James
