10-03-2013
Quote:
Originally Posted by
ckwan
1. Why most of time the File Cache in the memory seems constantly 100%?
It is memory which the system has borrowed to store file contents temporarily -- if you ask for the same file twice, reading it the second time is as fast as retrieving it from memory. It's just as good as Free, the system will give it up whenever needed.
There's at least two reasons why cache would be so high -- either this server is very idle, letting all memory gradually trickle into cache, or there's high levels of disk activity which push free memory into cache much faster.
Quote:
But why this is not happen in Datastage 2 and 3?
They are experiencing different loads. Maybe they have less disk activity, or maybe they're hosting RAM-hungry programs that leave very little room for cache (which is a bad thing, by the way -- cache is good for you).
Quote:
btw, Is File Cache is part of the memory or it is separated from memory ?
Cache is part of memory. The system has borrowed it to store file contents, but gives it back just as easily.
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LEARN ABOUT DEBIAN
cache::memory
Cache::Memory(3pm) User Contributed Perl Documentation Cache::Memory(3pm)
NAME
Cache::Memory - Memory based implementation of the Cache interface
SYNOPSIS
use Cache::Memory;
my $cache = Cache::Memory->new( namespace => 'MyNamespace',
default_expires => '600 sec' );
See Cache for the usage synopsis.
DESCRIPTION
The Cache::Memory class implements the Cache interface. This cache stores data on a per-process basis. This is the fastest of the cache
implementations, but is memory intensive and data can not be shared between processes. It also does not persist after the process dies.
However data will remain in the cache until cleared or it expires. The data will be shared between instances of the cache object, a cache
object going out of scope will not destroy the data.
CONSTRUCTOR
my $cache = Cache::Memory->new( %options )
The constructor takes cache properties as named arguments, for example:
my $cache = Cache::Memory->new( namespace => 'MyNamespace',
default_expires => '600 sec' );
See 'PROPERTIES' below and in the Cache documentation for a list of all available properties that can be set.
METHODS
See 'Cache' for the API documentation.
PROPERTIES
Cache::Memory adds the property 'namespace', which allows you to specify a different caching store area to use from the default. All
methods will work ONLY on the namespace specified.
my $ns = $c->namespace();
$c->set_namespace( $namespace );
For additional properties, see the 'Cache' documentation.
SEE ALSO
Cache
AUTHOR
Chris Leishman <chris@leishman.org>
Based on work by DeWitt Clinton <dewitt@unto.net>
COPYRIGHT
Copyright (C) 2003-2006 Chris Leishman. All Rights Reserved.
This module is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either expressed or implied. This program is free software;
you can redistribute or modify it under the same terms as Perl itself.
$Id: Memory.pm,v 1.9 2006/01/31 15:23:58 caleishm Exp $
perl v5.12.4 2011-08-05 Cache::Memory(3pm)