On 29 February 2012 16:59, Day, Robert <[email protected]> wrote:
> I’ve been dealing with this problem for some time. We have some large disks
> here that cannot be measured accurately in the hrStorageTable due to a 32
> bit integer being too small.
That's not strictly true.
The hrStorageTable uses two column objects to represent the size
of a disk partition (or other storage element) - hrStorageSize and
hrStorageAllocationUnits. Both of these are 32-bit values, but in
combination can handle elements up to 2^64 (16 exabytes)
If hrStorageAllocationUnits is fixed at 1 (i.e. individual bytes),
or 1024 (i.e. measured in K), then this will limit hrStorageSize
and similar to 2^32 = 2 Gb or 2^42 = 2 Tb respectively.
But the hrStorageTable can handle larger disks quite happily,
and more recent versions of the Net-SNMP agent are starting to
take advantage of this.
> I understand that when the value is too large,
> it raps the counter.
That is true of counter-based objects - but that's not really relevant
here. The only counters in the Host Resources MIB are two error
counters (hrStorageAllocationFailures and hrDeviceErrors).
The size metrics are simple Integer values - probably the most
sensible behaviour on overflow would be to latch at the maximum
value. (See the description of Gauge objects in SMI)
> Does net-snmp have any mib available similar to the
> hrStorageTable that shows disk logical disk information with 64 bit
> counters?
a) Forget about counters - they're not relevant here
b) The hrStorageTable can already handle larger disks - see above
c) The Net-SNMP specific 'dskTable' has entries which *are* limited
to 2Tb (i.e. 32-bit values, measured in Kb)
namely dskTotal, dskAvail and dskUsed.
However these are accompanied by equivalent "paired" objects
dskTotal{High,Low}, dskAvail{High,Low} and dskUsed{High,Low}
which provide 64-bit representations (again measured in Kb),
and so will handle disks up to 2 Zettabytes.
That should be sufficient for the forseeable future!
Dave
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