Oracle Database Appliance (ODA) is in many ways similar to an Exadata quarter rack: they both use two similar compute servers in an engineered system configuration, with shared storage and flash storage. But in other ways, especially networking and storage, they differ significantly. In particular:
- Storage connectivity: ODA uses SAS direct attachment, while Exadata uses an InfiniBand backbone connected to dedicated storage servers
- Flash memory: Exadata has significantly more flash memory than ODA does. While both can store ASM diskgroups in flash, Exadata also has flash cache capability. ODA’s default configuration uses flash to store redo logs; this helps compensate for ODA’s lack of
battery-backed disk write cache in the latency-sensitive redo write workload.
- Expandability: ODA currently comes in a single 2-server, 12TB configuration. An Exadata quarter-rack configuration has
2 compute servers and a minimum of 21TB raw storage. Both compute capacity and storage are expandable virtually without limit, given sufficient number of racks and network backbone.
The chart below summarizes the similarities and differences:
|Number of compute servers||2||2|
|Server type||X4370 M2||X4170 M2|
|Compute node expansion||None||Exadata half rack|
|OS||OEL 5.5||OEL 5.5|
|Flash usage||ASM diskgroup||Flash cache or ASM diskgroup|
|Cluster interconnect||2xGigE using Oracle Redundant Interconnect||InfiniBand, active-passive|
|External connectivity (per server)||2x10GigE, 4xGigE||2x10GigE, 4xGigE|
|Drive type||600G SAS||600G or 2TB SAS|
|Number of drives||20||36|
|Raw shared disk capacity||12TB||21.6TB (high speed) or 72TB (high capacity)|
|Storage expansion||None||Exadata half rack or additional storage servers|
|Local storage||2x500G SATA||4x300G SAS|
|RAM||96 GB/server||96 GB/server|
|CPU||2xX5675 3.06Ghz/server||2xX5675 3.06Ghz/server|
|Storage access||SAS||Oracle IDB over InfiniBand|
|Battery-backed write cache||None||512m/storage server|
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