I am trying to understand the difference between the SSD/Flash components located in various elements of Exalogic. I have read most of the Oracle docs and some of the blog stuff, but there is some confusion as Exadata drifts into the text. So it is not clear what is and isn't in Exalogic, and what function each of the SSD/Flash components perform.
There are SSDs in the nodes, and I believe they are used for fast OS load, fault data, but also swap space. How is the swap space used? Is this Database Smart Flash Cache?
In the Sunfire storage heads also have SSD, I believe 4TB for Read and 92GB for Write. How are these allocated? What is the mechanism for moving read/write data in and out of the SSDs? Is this Exadata Smart Cache running in the storage heads?
Any comments or points to other sources would be helpful.
Exalogic uses SSDs in three subsystems:
1) The Exalogic compute nodes each use 2 (two) SSDs in a RAID1 (mirrored) configuration for storage of the local boot image of the operating system
2) Each Exalogic storage head uses SSDs to implement the "Readzilla" read caches, which accelerate the READ performance of the storage system
3) The Exalogic Disk Array contains SSDs used to implement the "Logizilla" write cache, which accelerates WRITE performance of the storage system
- Michael Palmeter (Exalogic Product Management)