17587 FIX informix_dbspaces: fix calculation of free and used space size

Prior to this werk, the free and used space size was incorrectly calculated as the chunk pagesize was taken
instead of the dbspace default pagesize. This werk fixes this issue by querying the correct pagesize value. To
benefit from this change, the mk_informix plugin should be reinstalled with this new change. The check plugin
itself remains unmodified.

SUP-22249

Change-Id: Iece8cff4ba2b014185c492fd98fd845faa22bdb7

.werks/17587

@@ -0,0 +1,13 @@
+Title: informix_dbspaces: fix calculation of free and used space size
+Class: fix
+Compatible: compat
+Component: checks
+Date: 1739361730
+Edition: cre
+Level: 1
+Version: 2.2.0p40
+
+Prior to this werk, the free and used space size was incorrectly calculated as the chunk pagesize was taken
+instead of the dbspace default pagesize. This werk fixes this issue by querying the correct pagesize value. To
+benefit from this change, the mk_informix plugin should be reinstalled with this new change. The check plugin
+itself remains unmodified.

agents/plugins/mk_informix

@@ -170,6 +170,7 @@ informix_tabextents() {
 }
 
 informix_dbspaces() {
+    # the default dbspace pagesize must be taken to calculate the used and free space
     echo "<<<informix_dbspaces>>>"
     echo "[[[$INFORMIXSERVER/$SERVERNUM]]]"
     sql "select
@@ -179,7 +180,7 @@ informix_dbspaces() {
             sd.flags,
             'CHUNK',
             sc.fname,
-            sc.pagesize,
+            (select sh_pagesize from sysmaster:sysshmvals) pagesize,
             sc.chksize,
             sc.nfree,
             sc.flags,

checks/informix_dbspaces

@@ -2,6 +2,12 @@
 # Copyright (C) 2019 Checkmk GmbH - License: GNU General Public License v2
 # This file is part of Checkmk (https://checkmk.com). It is subject to the terms and
 # conditions defined in the file COPYING, which is part of this source code package.
+"""
+Relevant documentation:
+    * https://docs.deistercloud.com/content/Databases.30/IBM%20Informix.2/Monitoring.10.xml?embedded=true#51cf1eb453b73e7ffdd2172551fc58ed
+    * https://www.ibm.com/docs/en/informix-servers/14.10?topic=tables-syschunks
+"""
+
 
 factory_settings["informix_dbspaces_default_levels"] = {"levels_perc": (80.0, 85.0)}