A: Oracle recommends that you install Oracle ASR Manager on an external, standalone server.
C: Oracle ASR is designed to generate Oracle service requests automatically when certain types of faults are detected on Oracle products that are qualified for Oracle ASR.
Oracle ASR works only for specific component faults. Most of the common components, such as disks, fans, and power supplies, are covered. However, some components are not covered. For example, Oracle ASR does not cover InfiniBand events; there are specific images and specific InfiniBand switch firmware that you must use. You cannot upgrade these components independently.

A: IPMI - short for Intelligent Platform Management Interface - is an interface standard that allows remote management of a server from another using standardized interface.
The servers in the Exadata Database Machine follow that. It's not an Exadata command but rather a general Linux one.
To power on a cell or database server, issue this from another server:
# ipmitool -H prolcel01-ilom -U root chassis power on
To stop a server, use the shutdown command. To stop immediately and keep it down, i.e.
not reboot, execute:# shutdown -h -y now
C: Like the KCS interface, the SSIF Interface is only specified as a 'Single Threaded
Interface' for standard IPMI commands. That is, the BMC implementation is not expected to process more than one IPMI request at a time. While an implementation is allowed to have a degree of 'command queuing', for standard IPMI messages the SSIF lacks a 'Seq' field that software can use to match up particular instances of requests with responses.
References: https://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/ipmi-intelligent-platform-mgt-interface-spec-2nd-gen-v2-0-spec-update.pdf

A: To further accelerate OLTP workloads, the Exadata Smart Flash Cache also implements a special algorithm to reduce the latency of log write I/Os called Exadata Smart Flash Logging.
C: Use the Write-Back Flash Cache feature to leverage the Exadata Flash hardware and make Exadata Database Machine a faster system for Oracle Database Deployments.
D: Exadata X5-2 introduces Extreme Flash Storage Servers. Each Extreme Flash storage server contains eight 1.6 TB state-of-the-art PCI Flash drives. PCI flash delivers ultra-high performance by placing flash memory directly on the high speed PCI bus rather than behind slow disk controllers and directors.
References:
http://www.oracle.com/technetwork/database/exadata/exadata-x5-2-ds-2406241.pdf
http://www.oracle.com/technetwork/articles/database/exadata-write-back-flash-2179184.html

Metrics are a series of measurements that are computed and retained in memory for an interval of time, and stored on a disk for a more permanent history.
On the storage servers, the CELLSRV process provides the majority of Oracle Exadata storage services and is the primary storage software component. One of its functions is to process, collect, and store metrics. The Management Server (MS) process receives the metrics data from CELLSRV, keeps a subset of metrics in memory, and writes to an internal disk-based repository hourly.
References: http://www.oracle.com/technetwork/articles/servers-storage-admin/monitor-exadata-em12-
2291964.html