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.md

@@ -0,0 +1,17 @@
+[//]: # (werk v2)
+# informix_dbspaces: fix calculation of free and used space size
+
+key        | value
+---------- | ---
+date       | 2025-02-12T12:02:10+00:00
+version    | 2.5.0b1
+class      | fix
+edition    | cre
+component  | checks
+level      | 1
+compatible | yes
+
+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,

cmk/base/legacy_checks/informix_dbspaces.py

@@ -9,6 +9,12 @@
 from cmk.agent_based.legacy.v0_unstable import LegacyCheckDefinition
 from cmk.agent_based.v2 import render
 
+"""
+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
+"""
+
 check_info = {}