Common Terminology used in Exadata.

IB - InfiniBand
ILOM - Integrated Lights Out Manager
IPMI - Intelligent Platform Management Interface
LUN - Logical Unit Number
HARD - Hardware Assisted Resilient Data
RDS - Reliable Data Socket protocol
iDB - Intelligent Database protocol
UDMs - User Defined Metrics
IOPS - IOs Per Second
OEL - Oracle Enterprise Linux
SNMP - Simple Network Management Protocol
MS - Management Server
RS - Restart Server
EM - Enterprise Manager
EMGC - Enterprise Manager Grid Control
HCA - Host Controller Adapter
HBA - Host Bus Adapter
SM - Subnet Manager
DBRM - Database Resource Manager
SATA - Serial Advanced Technology Attachment
SAS - Serial Attached SCSI
CU - Compression Unit
PDU - Power Distribution Unit
HCC - Hybrid Columnar Compression

Source: Net

Regards
Gurudatta N.R