ES is basically a usability wrapper around Lucene. I've heard that Sphinx is better for a single node configuration, it's faster and uses less resources, but clustering with Sphinx is apparently tricky.
The other competitor, which I have no experience with is Solr, but this write-up http://karussell.wordpress.com/2011/05/12/elasticsearch-vs-s... gives an overview of the ES advantages over Solr.
I'm not a Full-Text Search expert, but a number of really smart people at my company evaluated a number of them for one of the most critical pieces of our production site and they chose ElasticSearch.
For logging searching is the major item at large sites IMO (talking terabytes at least), when you're looking for all occurrences of "item x" over..
"the past week", it may take 1H
"the past month", it may take 10-30H
"the past year", uh, no, you don't do that.
So you gotta use ranges, but it's often hard to guess and you end up missing many log entries just because you don't have the time to search through them.
(obviously loading gigabytes of indexed data takes a while "physically speaking" anyway. I'm guessing ES can distribute the load tho, much like a web search engine does)
I'm not sure what your question is, but I've experimented with loading netflow data in Solr and I'm averaging sub-2 second query times. That's on a laptop, with a couple of minutes of netflow (around 10Gb).
With proper indexing your search response time shouldn't increase lineally with your data size.
And i'm talking 100gb+ indexes ;-)
Obviously 2min of netflow data ain't much. I would want to see the result over 200h (or more) of netflow data, for example
Obviously 2min of netflow data ain't much
Depends where you work...
I just checked, and it was 2Gb of netflow I tested on. That seemed small, so I looked a bit deeper and indeed I was only using a small fraction of our total netflow for that period. Tt was adequate for what I was trying, though.