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From Sanyi <>
Subject Re: What is the best file system for Lucene?
Date Tue, 30 Nov 2004 13:23:47 GMT
> How large is the index?   If it's less than a couple of GByte then it 
> will be entirely in memory

It is 3GBytes big and it will grow a lot.
I have to search from the HDD which is very fast compared to the notebook's HDD.

Average seek time:
Notebook: 8-9ms
Desktop: 3.9ms

Data read:
Notebook: max. ~20MBytes/sec
Desktop: 60-80MBytes/sec

So, if the bottleneck is the HDD, it has to be 2x-3x faster on the desktop system.
Except if reiserfs is a lot slower than NTFS.

> For example (and this is only an example) looking up a hostname in the 
> DNS will take about the same time on almost any machine you can get hold of.

Ok, but I have very simple and pure tests and everything is measured part-by-part.
..and every parts speeds up a lot on the desltop system, except the lucene search part.

> You don't say how you're measuring search performance and you don't say 
> what you're seeing.

I call my java program from command line on both systems, like:
search hello
Then it searches for bravo and collects the elapsed milliseconds between every call to anything.
Then it displays the results. It is very simple.

> Also, what's the load on the system while you're 
> running the tests?   gkrellm on Linux is very useful as an overall view 
> -- are you CPU bound, are you seeing lots of disk traffic?   Is the 
> system actually more-or-less idle?

Thanx for the hint. Since my search searches for only 30 hits, it completes too fastly to
let me
monitor it real-time.
Anyway, if reiserfs will prove to be fast enough, I'll search for other reasons and will perform
longer tests for real-time monitoring.


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