The MIBs are considered "self documenting" but you have to be careful, some values are from array start and are cumulative.   My suggestion, is install SANHQ which will provide that level of info and a whole lot more.  SANHQ is available on the Equallogic support website.  Regards, 
I am using SNMPWALK to collect OIDs for my various EqualLogics (I monitor them for several customers). I am have great success on the whole but my biggest issue right now is determining what SNMP values are available for things like Volume Read Latency and Volume Write Latency. I have the below settings for the Member Latencies. Member Read Latency .1.3.6.1.4.1.12740.2.1.12.1.4.1. Member Write Latency .1.3.6.1.4.1.12740.2.1.12.1.5.1. I even have the Volume name (below), which suggests to me I am close but I need to be absolutely certain (since I charge for accurate reporting). .1.3.6.1.4.1.12740.5.1.7.1.1.4.  Can anyone help me? Is there a guide somewhere with any of this information?
SNMP Values for Volume Read/Write Latency