In my recent post entitled Exadata Database Machine X2-2 or X2-8? Sure! Why Not? Part I, I started to address the many questions folks are sending my way about what factors to consider when choosing between Exadata Database Machine X2-8 versus Exadata Database Machine X2-2. This post continues that thread.
As my friend Greg Rahn points out in his recent post about Exadata, the latest Exadata Storage Server is based on Intel Xeon 5600 (Westmere EP) processors. The Exadata Storage Server is the same whether the database grid is X2-2 or X2-8. The X2-2 database hosts are also based on Intel Xeon 5600. On the other hand, the X2-8 database hosts are based on Intel Xeon 7500 (Nehalem EX). This is a relevant distinction when thinking about database encryption.
In his recent post, Greg brings up the topic of Oracle Database Transparent Data Encryption (TDE). As Greg points out, the new Exadata Storage Server software is able to leverage Intel Advanced Encryption Standard New Instructions (Intel AES-NI) found in the Intel Integrated Performance Primitives (Intel IPP) library because the processors in the storage servers are Intel Xeon 5600 (Westmere EP). Think of this as “hardware-assist.” However, in the case of the database hosts in the X2-8, there is no hardware-assist for TDE as Nehalem EX does not offer support for the necessary instructions. Westmere EX will—someday. So what does this mean?
At first glance one would think there is nothing in common between TDE and compression. However, in an Exadata environment there is storage offload processing and for that reason roles are important to understand. That is, understanding what gets done is sometimes not as important as who is doing what.
When I speak to people about Exadata I tend to draw the mental picture of an “upper” and “lower” half. While the count of servers in each grid is not split 50/50 by any means, thinking about Exadata in this manner makes understanding certain features a lot simpler. Allow me to explain.
In the case of compressing data, all work is done by the upper half (the database grid). On the other hand, decompression effort takes place in either the upper or lower half depending on certain criteria.
In the case of encryption, the upper/lower half breakout is as follows:
That pretty much covers it and now we see commonality between compression and encryption. The commonality is mostly related to whether or not a query is being serviced via Smart Scan.
I was reminded recently by Oracle’s Director of Exadata development that there is extra synergy between compression and encryption when combining HCC and TDE. As I’ve pointed out on this blog before, HCC data is filtered in compressed form. If that data is also stored in encrypted form, a Smart Scan is able to filter out vast amount of encrypted data without even touching it. That is, HCC short-circuits a lot of decryption cost. And, even though Exadata is really fast, it is always faster to not do something at all than to shift into high gear and do it as fast as possible.
Filed under: Exadata, Exadata Compression and Encryption, Exadata Database Machine, Exadata Database Machine X2-8 HP Full Rack, Exadata Encryption, Exadata X2-8, Nehalem EX, oracle, Oracle Intel Integrated Performance Primitives, Westmere EP Tagged: Exadata, Oracle Exadata Storage Server, Oracle Exadata Storage Server Software, X2-2 vs X2-8