Answer : B
According to the web search results, I/O performance is a measure of how fast data can be transferred between a storage device and a host system1.It depends on various factors such as the type of storage device, the interface, the workload, and the response time12.
The four storage devices you mentioned are:
SCM: Storage Class Memory, a type of persistent memory that can retain data even when power is lost.It can support both byte-level and block-level data access and has speeds nearly as fast as DRAM3.
SSD: Solid State Drive, a type of flash-based storage device that uses NAND chips to store data. It has no moving parts and offers faster read/write speeds than HDDs.It can use different interfaces such as SATA or NVMe45.
DRAM: Dynamic Random Access Memory, a type of volatile memory that loses data when power is lost.It is used as main memory in computers and offers very fast access speeds but consumes more power than SCM3.
SATA: Serial ATA, an interface standard for connecting storage devices such as HDDs or SSDs to a host system.It offers lower bandwidth and performance than NVMe but is more widely compatible4.
the correct order of I/O performance from lowest to highest among these storage devices isB. SATA--> SSD--> SCM --> DRAM. This is because SATA has lower bandwidth than NVMe which most SSDs use; SSDs have lower latency than HDDs but higher latency than SCM; SCM has lower latency than SSDs but higher latency than DRAM; and DRAM has the lowest latency and highest bandwidth among them all.
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