storage_free not correctly shown on linux servers

Dear,

we have a subscription observium ver. 0.14.10.5902(stable) and more than 400 devices connected. We saw that for linux servers 'disk_free' parameter is not correctly shown. Example:
-on debian 7 server:
rootfs 67840600 63365072 1029412 99% /

Observium databases (storage-state table) sais:
storage_id storage_polled storage_size storage_units storage_used storage_free storage_perc :
343 1414504366 69468774400 4096 64885837824 4582936576 93
(storage table):
storage_id device_id storage_mib storage_index storage_type storage_descr storage_hc storage_deleted:
343 192 host-resources-mib 32 hrStorageFixedDisk / 0 0
Also on centos servers same issue.

In other monitoring tools I saw that ucd-snmp-mib MIB is used. Is it possible to change mib poller from host-resources-mib to ucd-snmp-mib?

So, the problem is that on the server is only 1006M (1 GB) free disk space, and on observium GUI is 4.27 GB free, and alert checks not working for us.

Thanks in advance!