Six Tips for Selecting SSD and HDDs

Nexsan Corporation announced a new paper titled 6 Tips for Selecting HDD and SSD Drives.

The free educational resource provides guidance on selecting the most appropriate HDD or SSD technology when configuring a storage system for business applications.

There are a number of factors to be considered when selecting drives for a storage environment. These include the level of sequential or random access performance needed, storage density, reliability and cost. With today’s wide variety of storage devices, many IT professionals are challenged with the multitudes of drive technologies. This is especially true when selecting the appropriate drives for various data types. Adding to the confusion is that SATA and SAS refer to disk drive interfaces, whereas SSD refers to a particular kind of internal technology. Selecting a drive technology and interface type can seem complex with considerations of random access performance, sequential performance, cost, density and reliability, but is manageable with the right guidance.

With more than 28,000 storage systems in the field accounting for hundreds of thousands of drives shipped, the storage system experts at Nexsan have experience in determining the best and most reliable HDDs and SSDs for specific applications.

According to the company, by observing the following tips on drive selection, confusion over drive choice can be significantly reduced.

Do not confuse disk interface type
with performance or reliability
Historically, SAS and SATA were used as convenient shorthand for fast or dense disk drives, respectively. Now, however, there are SSD drives with SATA interfaces as well as inexpensive and dense but relatively low-IOPS 7200 RPM drives with SAS or even FC interfaces.

Achieve the best price/GB
with 3.5" 7200 RPM SATA drives
Storage vendors have a seemingly endless variety of pricing models, but one constant seems to be that 2.5" systems cost twice as much per gigabyte as 3.5" systems, assuming both are using ‘enterprise-grade’ drives. But as noted previously, a 3.5" drive will be far more reliable.

Understand that HDD performance
is mostly dictated by density and mechanical speed
The random or transactional (IOPS) performance of spinning drives is dominated by the access time, which in turn, is determined by rotational latency and seek time. Interface performance has almost no impact on IOPS. Additionally, interface speed has no measurable impact on sustained performance.

Consider SSD drives instead of 10K or 15K drives
for transactional workloads
Today it is very likely that an all-SSD storage solution will have lower overall capital and operational cost than one made from 15,000 RPM drives due to the reduction in total slots required to achieve a given transaction performance. Additionally, SSDs have a greatly reduced power footprint compared to spinning drives for a given number of transactions.

When building systems with high sequential performance
for applications such as video, 3TB 7200 RPM SATA drives
are better than SSD or 10K/15K drives
Somewhat surprisingly, neither SSDs nor 10,000/15,000 RPM disk drives are better for video and other streaming media applications than 7200 RPM SATA drives, unless there are numerous independent streams being written or read from the same RAID set.

Pay close attention to how much
your storage system supplier
treats the subject of disk drives
In the spirit of chasing profits, many storage system vendors are moving to a logistics model where drives are not tested in the storage array until it arrives at the customer site. Some no longer perform specific qualification checks between drive hardware and firmware revisions, and the hardware and firmware revisions of all the components of the storage array. This can result in less than stellar outcomes from the start.

"Hardware matters, and organizations intent on maintaining a robust storage environment should not underestimate the importance of optimizing storage infrastructure with quality hardware components and technology that is aligned with the operating environment," said Arun Taneja, Founder and Consulting Analyst, Taneja Group. "While technologies have matured to the point where hard drive downtime does not impact business continuity, missteps in drive selection can wreak havoc on operational performance and result in ongoing maintenance issues. We applaud Nexsan’s focus on educating the market in this often overlooked area."

"Correct drive choice plays a major role in the overall reliability and performance of a storage system," said Gary Watson, CTO, Nexsan. "At Nexsan, our processes ensure that only drive models performing well in exhaustive engineering trials and testing are delivered to the customer. Equally important, Nexsan’s partner ecosystem works with end users to match drives to their intended application, ensuring our systems perform optimally in any business environment."

To download 6 Tips for Selecting HDD and SSD Drives (you need to register)