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: vfunst...@gmail.com
> To: java-user@lucene.apache.org
>
> I was referring to *RAMDirectory*.
>
> On Wed, Jul 18, 2012 at 11:04 PM, Lance Norskog <goks...@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 <t...@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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> >
> >
> >
> > --
> > Lance Norskog
> > goks...@gmail.com
> >
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> >
