[Solved] Cacti Won't Graph Large Disk Volumes Over 8 TB/TeraByte

Last Updated: 3/4/11

These are the facts (IMHO):

- Cacti has trouble graphing disks over 8 TB with a StorageAlocationUnit (aka Cluster) of 4096.
- The problem is that the SNMP counter is 32-bit signed integer
- The behavior does not change between a 32bit Windows server and a 64bit windows server
- My original equation was wrong, the correct equation is: ($snmp_data + 4294967296) * $sau;
- This is a workaround and still has a maximum size of 16 TB. Over 16 TB will have unknown results.
- Posted below is a patched version of the script for Cacti Version 0.8.7e (ss_host_disk.php)

Notes:
I am running Cacti Version 0.8.7e
Sample Graph below (you can see where I fixed the bug in the script and values changed)
Changing the cluster size of the filesystem to greater than 4096 may help resolve the issues without modifying Cacti.

fixed graph 10tb volume.png

Attached Files:
ss_host_disk.zip (2284 downloads)

Keywords: cacti, nan, large disk, terabyte volume, graph, incorrect