Database Reference
In-Depth Information
Table 5-1.
Storage RAID configuration design
RAID Group Name
RAID Level
Number of Disks
Volumes
DataG1
10
4
Data1, OCR1
DataG2
10
4
Data2, OCR2
DataG3
10
4
Data3, OCR3
Redog1
1
2
Redo1
Redog2
1
2
Redo2
Figure 5-3.
An example of storage RAID configuration for RAC Database
Storage Protocols
Apart from RAID configuration, it is a critical part of storage design to determine how the RAC node hosts share access
to the storage and perform database I/O operations through the storage. This design includes the topology of physical
links between the hosts and the storage and storage protocols that are used to transfer the data. Here we explore some
widely used storage network protocols such as Small Computer System Interface (SCSI), Fibre Channel (FC), Internet
Protocol (IP), and Network Area Storage (NAS). SCSI, FC, and IP protocols send block-based data, called the block
base protocol, while NAS sends file-based data across the network, called the file-based protocol.
The SCSI protocol defines how host operating systems do I/O operations on disk drives. In the SCSI protocol, the
data is sent in a chunk of bits called a “block” in parallel over a physical connection such as a copper SCSI cable. Every
bit needs to arrive at the other end of cable at the same time. This limits the maximum distance between the host and
the disk drives to under 25 meters. In order to transfer the data over a longer distance, the SCSI protocol usually works
with other protocols such as FC and Internet SCSI (iSCSI).
