Decisions about how to configure storage software or design and hardware usually consider performance. Performance is degraded or improved as a result of trade-offs between multiple factors such as cost, availability, reliability, power, or ease-of-use. There are many components
involved in handling storage requests as they work their way through the
storage stack to the hardware, and trade-offs are made between such factors at
each level.File file system architecture, cache management, ,and volume
management translate application calls into individual storage access requests.
These requests traverse the storage driver stack and generate streams of
commands that are presented to the disk storage subsystem. The sequence and
quantity of calls and the subsequent translation can improve or degrade
performance.
Fig 4 shows the storage architecture, which includes
many components in the driver stack.
Choosing Storage
Most important considerations in preferring storage
systems include:
· Understanding that application behavior is essential for storage subsystem planning and performance analysis.
·
Understanding the characteristics of current and
future storage workloads.
· Selecting a data layout scheme (such as striping), redundancy architecture (such as mirroring), and backup strategy.
·
Providing necessary storage space, bandwidth,
and latency characteristics for current and future needs.
·
Using a procedure that provides the required
performance and data recovery capabilities.
·
Using power guidelines; that is, calculating the
expected average power required in total and per- unit volume (such as watts per
rack).
For better understanding the workloads on a specific
server or set of servers, the more accurately you can plan. The following are
some important workload characteristics:
· Sequential vs. random access
· Write ratio vs. Read
· Request concurrency,patterns of request arrival rates and inter arrival rates
·
Typical request sizes
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