9. Disks

Disk I/O can cause significant application latency and is therefore an important target of systems performance analysis. Under high load, disks become a bottleneck, leaving CPUs idle as the system waits for disk I/O to complete. Identifying and eliminating bottlenecks can improve performance and application throughput by orders of magnitude.

The term disks refers to the primary storage devices of the system. They include magnetic rotating disks and flash-memory-based solid-state disks (SSDs). The latter were introduced primarily to improve disk I/O performance, which they do. However, demands for capacity and I/O rates are also increasing, and flash memory devices are not immune to performance issues.

This chapter consists of five parts, ...

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