Database Reference
In-Depth Information
Figure 12-8.
OEM showing high I/O activity
The storage system should be verified to ensure that all disks in the storage array are of high-performing
(tier one) storage. While it may be difficult to have the entire storage array contain disks of the same performance
characteristics, care should be taken to ensure that disks within a disk group have identical capacity and performance
characteristics. A poor-performing disk in a disk group can create inconsistent I/O activity. When using Automatic
Storage Management (ASM), performance characteristics of the individual disks within a diskgroup can be monitored
using EM (see section “Enterprise Manager to Monitor Storage”).
Types of I/O Operations
Depending on the measurements we are trying to capture and the statistics we are trying to analyze, I/O can be
categorized as belonging to one of the following:
•
Read vs. write
•
Single-block vs. multi-block
•
Random vs. sequential
•
Synchronous vs. asynchronous
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