<?php

if (! is_array($storage_cache['zpool'])) {
    $storage_cache['zpool'] = snmpwalk_cache_oid($device, 'zpoolTable', null, 'FREENAS-MIB');
    d_echo($storage_cache);
}

foreach ($storage_cache['zpool'] as $index => $entry) {
    $storage['units'] = $entry['zpoolAllocationUnits'];
    $storage['size'] = ($entry['zpoolSize'] * $storage['units']);
    $storage['free'] = ($entry['zpoolAvailable'] * $storage['units']);
    $storage['used'] = ($storage['size'] - $storage['free']);
}