Hey Michael,
The OCI DWH has VM performance data, I believe in OCI 7.0.2. There is no data mart built in Cognos, but the data is available via SQL. By default, I believe the DWH will have:
2 weeks hourly data
Far longer daily data
for each VM
OCI 7.0.1 and higher has REST API acccess to VM performance data out of the operational OCI server. As noted, OCI defaults to storing 7 days of performance data, which for VMs is probably at 5-15 minutes granularity by default (haven't had coffee yet, and should be jumping in the shower instead of answering questions.
Matt