83 lines
4.9 KiB
HTML
83 lines
4.9 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
<html lang="en-us" xml:lang="en-us">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<meta name="security" content="public" />
|
|
<meta name="Robots" content="index,follow" />
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
|
<meta name="DC.Type" content="task" />
|
|
<meta name="DC.Title" content="Managing media capacity on a per-file basis" />
|
|
<meta name="abstract" content="Learn how to manage media capacity on a per-file basis." />
|
|
<meta name="description" content="Learn how to manage media capacity on a per-file basis." />
|
|
<meta name="DC.Relation" scheme="URI" content="tipsandtechniques.htm" />
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 2000, 2006" />
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2000, 2006" />
|
|
<meta name="DC.Format" content="XHTML" />
|
|
<meta name="DC.Identifier" content="capacitymanage" />
|
|
<meta name="DC.Language" content="en-us" />
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
|
<!-- US Government Users Restricted Rights -->
|
|
<!-- Use, duplication or disclosure restricted by -->
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
|
<title>Managing media capacity on a per-file basis</title>
|
|
</head>
|
|
<body id="capacitymanage"><a name="capacitymanage"><!-- --></a>
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
|
<h1 class="topictitle1">Managing media capacity on a per-file basis</h1>
|
|
<div><p>Learn how to manage media capacity on a per-file basis.</p>
|
|
<div class="p"><div class="p">An application might need to manage the media capacity on a per-file
|
|
basis. Following are a few methods you can use to decide if a file will fit
|
|
on the media: <ol><li>Handle error on a close operation <p>Assume an optical volume is initialized
|
|
to a 95% threshold and an application writes files until the volume threshold
|
|
is reached. When the threshold is reached, the application will receive message
|
|
CPF1F61, <kbd class="userinput">No free space available on media</kbd>. At this
|
|
point, the volume threshold can be increased to 97% (or anything else up to
|
|
100%) by using the CHGOPTVOL command. You can then attempt to close the file.</p>
|
|
</li>
|
|
<li>Specify QALCSIZE on the Open Stream File HFS API <div class="p">Another method to
|
|
determine if a file will fit on a volume is by specifying an allocation size
|
|
(QALCSIZE) on an open stream file. On an open stream file, the system can
|
|
pass a value in attribute QALCSIZE. This attribute is valid when the open
|
|
operation is for create or replace; otherwise, it is ignored. Specifying a
|
|
value for QALCSIZE results in comparing the specified value against the space
|
|
available on the volume. If the space available is less than QALCSIZE, then
|
|
the system issues message CPF1F61. The space available must exceed the QALCSIZE
|
|
in order for the open operation to occur. Only on the first open instance
|
|
of a file honors this attribute. If specified by more than one opening of
|
|
a file, the system ignores the additional attributes. <div class="note"><span class="notetitle">Note:</span> This does not
|
|
actually allocate space on the optical volume at the time of the open operation.
|
|
It checks the volume to see if the number of requested bytes
|
|
are available.</div>
|
|
</div>
|
|
<div class="p">There are drawbacks to using this method: <ol type="a"><li>You need to know the size of the file you are creating at the time you
|
|
make the open request.</li>
|
|
<li>If multiple jobs are writing to the same media, there is no guarantee
|
|
that by the time the data is written, the space will still be available.</li>
|
|
</ol>
|
|
</div>
|
|
<p>If the size of the file is known prior to the time the open request
|
|
is made, and there will not be other jobs writing to that volume during the
|
|
time your file is open, this is an excellent method to check media capacity
|
|
before creating a file.</p>
|
|
</li>
|
|
<li>Retrieve space available on a volume <p>Another method is to have the
|
|
application retrieve the space available on the volume. You can do this by
|
|
using the Display Optical (DSPOPT) command through output file support. The
|
|
output file can then be read to retrieve the number of bytes assumed to be
|
|
available on the media.</p>
|
|
</li>
|
|
</ol>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div>
|
|
<div class="familylinks">
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="tipsandtechniques.htm" title="The following techniques are often helpful in designing custom optical programs for your business.">Tips: Optical programming</a></div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html> |