Disk IO (Host MIB) - help pls

[five0.4tluv]

I'm having issues with this also. My Bytes graphs are NaN and my transactions graphs seem reversed. I'm not able to determine why my Bytes are not working. The transactions I believe are reversed because I know when my backups run on a particular host that I'm graphing and during the backup window the IO shows more writes than reads. all snmp queries seem to be fine also.