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From Dragon Fly <dragon-fly...@hotmail.com>
Subject RE: RAM or SSD...
Date Fri, 20 Jul 2012 11:32:54 GMT

Thank you.

> From: dawid.weiss@gmail.com
> Date: Thu, 19 Jul 2012 13:34:26 +0200
> Subject: Re: RAM or SSD...
> To: java-user@lucene.apache.org
> 
> Read this:
> http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html
> 
> Dawid
> 
> On Thu, Jul 19, 2012 at 1:32 PM, Dragon Fly <dragon-fly999@hotmail.com> wrote:
> >
> > The slowest part of my application is to read the search hits from disk.  I was
hoping that using an SSD or RAMDirectory/MMapDirectory would speed that up.  I read the JavaDoc
for MMapDirectory but didn't really understand how that differs from RAMDirectory.  Could
someone please explain?
> >
> >> Date: Wed, 18 Jul 2012 23:46:51 -0700
> >> Subject: Re: RAM or SSD...
> >> From: vfunstein@gmail.com
> >> To: java-user@lucene.apache.org
> >>
> >> I was referring to *RAMDirectory*.
> >>
> >> On Wed, Jul 18, 2012 at 11:04 PM, Lance Norskog <goksron@gmail.com> wrote:
> >> >> You do not want to store 30 G of data in the JVM heap, no matter what
> >> library does this.
> >> > MMapDirectory does not store data in the JVM heap. It lets the
> >> > operating system manage the disk buffer space. Even if the JVM says "I
> >> > have 30G of memory space", it really does not. It only has address
> >> > space allocated by the  OS but no memory.
> >> >
> >> > On Wed, Jul 18, 2012 at 10:39 PM, Toke Eskildsen <te@statsbiblioteket.dk>
> >> wrote:
> >> >> On Wed, 2012-07-18 at 17:50 +0200, Dragon Fly wrote:
> >> >>> If I want to improve performance, which of the following is better
and
> >> why?
> >> >>>
> >> >>> 1. Buy a machine with a lot of RAM and use a RAMDirectory for the
index.
> >> >>
> >> >> As others has pointed out, MMapDirectory should work better than
> >> >> RAMDirectory. I am sure it will work fine with a relative small index
> >> >> such as yours. However, it does not scale that well with index size.
> >> >>
> >> >>> 2. Put the index on a solid state drive.
> >> >>
> >> >> Why anyone buys computers without SSD's is a mystery to me. Use SSDs
for
> >> >> the small low-latency stuff and a secondary spinning drive for the
large
> >> >> slow stuff. Nowadays, a 30GB index (or 100GB for that matter) falls
into
> >> >> the small low-latency bucket. SSDs speeds up almost everything, saves
> >> >> RAM and spares a lot of work hours optimizing I/O-speed.
> >> >>
> >> >> Regards,
> >> >> Toke Eskildsen
> >> >>
> >> >>
> >> >> ---------------------------------------------------------------------
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> >> >> For additional commands, e-mail: java-user-help@lucene.apache.org
> >> >>
> >> >
> >> >
> >> >
> >> > --
> >> > Lance Norskog
> >> > goksron@gmail.com
> >> >
> >> > ---------------------------------------------------------------------
> >> > To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> >> > For additional commands, e-mail: java-user-help@lucene.apache.org
> >> >
> >
> 
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> 
 		 	   		  
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