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SSD vs HDD - Which one is better performing?

Published by admin in the blog admin's blog. Views: 955

Much hype is given to SSD performance and SSD is considered to be the next generation storage devices. The objective of our testing was to test the performance of an SSD in a real-world environment against workloads like OLTP, DSS etc., and to compare their performance with the traditional hard disk drives.

Drive Specifications – SSD
Cost – 9000$, Make – HP, Interface – SAS,

Drive Specifications – HDD
Cost – 500$ , Make – HP, Interface – SAS

SSD vs HDD – An Overview

A solid-state drive (SSD) is a high performance plug-and-play data storage device which uses integrated circuit assemblies as memory to store data persistently. Unlike traditional disk drives, SSD does not have any movable part which makes it more durable and shock resistant. Other than memory chips, SSD has its own memory bus, a CPU and a battery card. Due to presence of an internal CPU, SSDs can manage their data storage and hence, they are a lot faster than conventional rotating hard disks and produce highest possible I/O rates.

Features of SSD
Extremely low access times:
SSDs have extremely low access times, as they don't require the storage medium to spin up for data access. Thus, all data on an SSD can be accessed instantaneously without the delays of mechanical "seek" times.
Durable and shock-resistant:
SSD have a non-mechanical design consisting of NAND flash chips which makes them more durable and more shock resistant than traditional hard disk drives.
SSDs can have a much faster performance, almost instantaneous data access, quicker boot ups, faster file transfers, and an overall snappier computing experience than hard drives. HDDs can only access the data faster the closer it is from the read write heads, while all parts of the SSD can be accessed at once.
Cooler and Quieter:
With no moving parts, SSDs run at near silent operation and require very little power to operate that translates into significantly less heat output by your system.

Parameters Considered for Benchmarking

Various parameters that should be considered when evaluating the performance of SSDs are:
1. # of Outstanding I/O (or Queue depth)
2. Request Size
3. Read/Write ratio
4. Transfer ratio (Random/Sequential)

Tool Used For Comparing Performance

Tool used for bench marking - For evaluating the disk I/O performance, the most widely used tool is Iometer. The main reason for this being it is an open source tool and is readily available (You can download it from http://www.iometer.org ). The other reason is that, with Iometer almost any type workload mix can be generated and tested on the drives

Iometer can be used for measurement and characterization of:

  • Performance of disk and network controllers.
  • Bandwidth and latency capabilities of buses.
  • Network throughput to attached drives.
  • Shared bus performance.
  • System-level hard drive performance.
  • System-level network performance.

Drive Specifications Used For Comparing Performance


Load Profiles Used for simulating Loads

Various types of load profiles were used to generate sppecific app workloads to compare performance between SSD and HDD. These profiles resemble the typical disc workloads of popular application types like - File Copy, Backup, Database, OLTP etc


Test Results - OLTP :

We oserved that SSD drives outperform HDD drives - Below IOPS distribution clearly shows that SSD stands out a clear winner. Improvement provided by SSD is about 16 times better than HDD’s performance.


Test Results - BACKUP Application:
A Backup workload is represented by large block sequential reads. SSD does not have much improvement over HDD but then also, it is almost twice.


Test Results - Restore Application:

A Backup workload is represented by large block sequential reads. SSD does not have much improvement over HDD but then also, it is almost twice.


Test Results - File Copy Application:

File copying generally refers to creating a new file which has the same content as the existing file. By definition you can note that, it is actually performing a read operation on the existing file and writing into the new file created. SSD provides almost 10 times improvements over HDD.

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