My First Words About Oracle Exadata X3 In-Memory Database Machine

I’ve had countless emails from readers asking for a technical analysis of what Oracle announced at Openworld 2012 pertaining to the X3 refresh of Exadata Database Machine. I attended the show, fell ill and subsequently had a a lot of work backlog to clear. I will get to this next week and, not surprising to readers of this blog, I’ll take aim on  the following words: “Database In-Memory Machine” as they appear in the new marketing nickname for Exadata Database Machine.

Yes, I will blog the matter but would first like to recommend the following excellent blog posts by @flashdba as they relate to “Database In-Memory Machine”:

In Memory Databases Part I

In Memory Databases Part II

Note: Part II has one tiny bit of errata as discussed in the comment section of the post. The post speaks of the cache hierarchy of X3 and includes Exadata Storgage Server DRAM in the aggregate. I need to point out that the DRAM in Exadata Storage Server cells is not used for cache. DRAM in the storage servers is used for management (metadata) of Exadata Smart Flash Cache contents, Storage Indexes buffering (storage read buffers, HC decompression output and send buffers, etc). The cache hierarchy of X3 is quite succinctly host DRAM (SGA buffers and Results Cache) and Exadata Smart Flash Cache (the PCI flash devices accessed via SCSI disk driver through the Linux block I/O layer in the cells).

Very Important Background Information
The freshly-updated Oracle Exadata Database Machine X3 has the same fundamental architecture as X2. Additionally, the performance characteristics of the infiniband network used for data flow from storage to database hosts remains at 40Gb QDR (same as X2). Therefore I urge all to spend the time it takes to view my Critical Thinking instructional videos on Exadata architecture. As a hint to my up-coming blog series on the matter, I’ll point out that the supposed “In-Memory” assets in this “new” Exadata X3 In-Memory Database Machine just so happen to be housed in the storage grid–not the database grid. To that end, a good understanding of how data flow works in X2 and X3 Exadata is critical to fully appreciate just what the term “In-Memory” means to Oracle Corporation.

Click here to access the Exadata Critical Thinking instructional videos.

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