07-06-2012
There are two major concepts in LVM to grasp:
Striping.
Where you deliberately create a Logical Volume across partitions on multiple physical discs. This can give a dramatic performance improvement.
Mirroring.
Where you have one (or preferably more) mirror copies of your critical Logical Volumes on totally different physical disc drives.
Disc drives do fail. With careful design for resilience you can keep running with a failed disc drive and replace a hot-pull disc without interruption to service. Taking this concept further you can fit multiple hot spare disc drives and configure the LVM system to automatically replace the failed disc drive.
Given the option of performance against resilience I would choose resilience every time.
Don't forget to check your server for failed disc drives at least once a day.
Ps. Checking resilent Disc Arrays is equally important because a failure will not be visible to your unix system.
Last edited by methyl; 07-06-2012 at 05:30 PM..
Reason: typos, layout, Ps
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LEARN ABOUT DEBIAN
cddb::file
CDDB::File(3pm) User Contributed Perl Documentation CDDB::File(3pm)
NAME
CDDB::File - Parse a CDDB/freedb data file
SYNOPSIS
my $disc = CDDB::File->new("rock/f4109511");
print $disc->id, $disc->all_ids;
print $disc->artist, $disc->title;
print $disc->year, $disc->genre, $disc->extd;
print $disc->length, $disc->track_count;
print $disc->revision, $disc->submitted_via, $disc->processed_by;
foreach my $track ($disc->tracks) {
print $track->number, $track->title, $track->artist;
print $track->length, $track->extd;
}
DESCRIPTION
This module provides an interface for extracting data from CDDB-format data files, as used by freedb.
It does not read data from your CD, or submit information to freedb.
METHODS
new
my $disc = CDDB::File->new("rock/f4109511");
This will create a new object representing the data in the file name specified.
id / all_ids
my $discid = $disc->id;
my @discid = $disc->all_ids;
Due to how freedb works, one CD may have several IDs associated with it. 'id' will return the first of these (not necessarily related to
the filename from which this was read), whilst 'all_ids' will return all of them.
title / artist
The title and artist of this CD. For eponymous CDs these will be identical, even if the data file leaves the artist field blank.
year
The (4-digit) year of release.
genre
The genre of this CD. This is the genre as stored in the data file itself, which is not related to the 11 main freedb genres.
extd
The "extended data" for the CD. This is used for storing miscellaneous information which has no better storage place, and can be of any
length.
length
The run time of the CD in seconds.
track_count
The number of tracks on the CD.
revision
Each time information regarding the CD is updated this revision number is incremented. This returns the revision number of this version.
processed_by / submitted_via
The software which submitted this information to freedb and which processed it at the other end.
tracks
foreach my $track ($disc->tracks) {
print $track->number, $track->title, $track->artist;
print $track->length, $track->extd;
}
Returns a list of Track objects, each of which knows its number (numering from 1), title, length (in seconds), offset, and may also have
extended track data.
Tracks may also contain an 'artist' field. If this is not set the artist method will return the artist of the CD.
SEE ALSO
http://www.freedb.org/
AUTHOR
Tony Bowden
BUGS and QUERIES
Please direct all correspondence regarding this module to:
bug-CDDB-File@rt.cpan.org
COPYRIGHT
Copyright (C) 2001-2005 Tony Bowden. All rights reserved.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License; either version 2 of the License,
or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.
perl v5.10.1 2005-10-04 CDDB::File(3pm)