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I'm not sure if this is just a quirk of how ZFS ZPL is presenting the available space, but it seems that SNMP is reporting the free space no more than 2TB higher than the used space.

This is on a mount that has no quota or reservation set, just a simple zpool create and then filling with data over time.

enter image description here

The total space in that pool is actually 6TB.

I wondered if maybe it could be happening because of an integer type used in my Cacti graph template.

Any ideas?

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Are you presenting the ZFS storage via NFS? – ewwhite May 26 '12 at 16:16
Nope this is SNMP direct to the server. Out of curiosity though, what diff would that make? – SimonJGreen May 26 '12 at 16:35
up vote 1 down vote accepted

Snmp doesn't handle ZFS correctly at all afaik. you are better off doing some scripting and extending snmp.

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Are you able to elaborate why that is? – SimonJGreen May 28 '12 at 12:58

Looks to me more like a net-snmp problem. More specifically, a 32 bit limit in the MIB. Look for some details in There are a few other pages relating to this problem, easily googled. I have a similar graph problem with a server running ext4, with a 12TB disk (used for Bacula backups).

Still searching for a solution for that problem....

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