Expert Oracle Exadata - Parent Directory

CHAPTER 1 WHAT IS EXADATA?Adapters. All but the smallest (quarter rack) Exadata configurations also contain a third InfiniBandswitch, intended for chaining multiple Exadata racks together. This switch is generally referred to as a“spine” switch.Flash CacheAs mentioned earlier, each storage server comes equipped with 384GB of flash-based storage. Thisstorage is generally configured to be a cache. Oracle refers to it as Exadata Smart Flash Cache (ESFC).The primary purpose of ESFC is to minimize the service time for single block reads. This feature providesa substantial amount of disk cache, about 2.5TB on a half rack configuration.DisksOracle provides two options for disks. An Exadata Database Machine may be configured with eitherhigh-capacity drives or high-performance drives. As previously mentioned, the high-capacity optionincludes 2TB, 7200 RPM drives, while the high-performance option includes 600GB, 15000 RPM SASdrives. Oracle does not allow a mixture of the two drive types. With the large amount of flash cacheavailable on the storage cells, it seems that the high-capacity option would be adequate for most readheavy workloads. The flash cache does a very good job of reducing the single-block-read latency in themixed-workload systems we’ve observed to date.Bits and PiecesThe package price includes a 42U rack with redundant power distribution units. Also included in theprice is an Ethernet switch. The spec sheets don’t specify the model for the Ethernet switch, but as of thiswriting they are shipping a switch manufactured by Cisco. To date, this is the one piece of the packagethat Oracle has agreed to allow customers to replace. If you have another switch that you like better, youcan remove the included switch and replace it (at your own cost). The X2-2 includes a KVM unit as well.The package price also includes a spares kit that includes an extra flash card, an extra disk drive, andsome extra InfiniBand cables (two extra flash cards and two extra disk drives on full racks). The packageprice does not include SFP+ connectors or cables for the 10GB Ethernet ports. These are not standardand will vary based on the equipment used in your network. The ports are intended for externalconnections of the database servers to the customer’s network.Software ComponentsThe software components that make up Exadata are split between the database tier and the storage tier.Standard Oracle database software runs on the database servers, while Oracle’s relatively new diskmanagement software runs on the storage servers. The components on both tiers use a protocol callediDB to talk to each other. The next two sections provide a brief introduction to the software stack thatresides on both tiers.Database Server SoftwareAs previously discussed, the database servers run Oracle Linux. Of course there is the option to runSolaris Express, but as of this writing we have not seen one running Solaris.12