Why You Should Move Your Databases from HDD to Flash

More and more companies have begun adopting flash hardware in the form of solid-state drives (SSDs) due to their undeniable performance benefits. While nearly every application can benefit from SSD technology, their price and limited capacity compared to spinning hard disk drives (HDDs) has led many IT administrators to employ only a small footprint of SSD hardware in order to accelerate performance of specific applications. SSDs have proven to be especially beneficial for database acceleration due to the generally high performance requirements and low capacity of database applications. Here we’ll take a look at the performance and reliability advantages of hosting your database applications on SSD technology opposed to legacy HDD hardware.

Performance is undoubtedly the greatest benefit realized from shifting database applications from HDD to flash technology. The performance differences between these two technologies is astonishing – whereas a single 15k SAS HDD drive may produce up to 300 IOPS (input/output per second), a single SSD can generate over 20,000 IOPS. Capacity aside, this would effectively translate to over 60 HDDs’ worth of performance and several rack units’ worth of physical space. While the tremendous performance benefits of SSD technology are widely known, an often overlooked benefit of SSDs is the consistency of the performance. HDDs write data from the outer tracks of the drive platter inward toward the middle of the platter, meaning that as a drive becomes full, the arm must move further to retrieve (read) or write data to the disk. The movement of the arm to the correct position is known as seek time and increases as more data is placed on the drive. Seek time combined with latency (the time it takes the disk to spin underneath the head to the correct location) can add up to well over 15ms worth of total latency. SSDs, on the other hand, are entirely electronic with no moving parts, meaning their performance remains consistent throughout their life since writes and reads to and from the drives are unhindered by mechanical limitations. The total latency for an SSD is a fraction of an HDD, (usually around sub-1ms). Implementing SSDs for IO-intensive databases will have an instantaneous and noticeable impact on their performance and may also indirectly accelerate other applications’ performance by relieving the burden that the databases had previously placed on them. While the performance benefits of implementing SSDs for databases are clear, the reliability of flash technology is also worth mentioning when considering the critical nature of databases.

Databases are the lifeblood of nearly every organization. Whether it be SQL, Oracle, Exchange, DB2, or any type of EMR, virtually every company heavily relies on their databases in order to conduct day to day business operations. With this being the case, the reliability of the hardware on which these databases reside is just as vital as the data residing within them. SSDs are significantly more reliable than HDDs due to their complete lack of moving parts in order to operate. Over time, HDDs begin to accrue medium errors which ultimately lead to drive failure and possible data corruption. Medium errors are discrepancies between what the HDD intends to write and what is actually physically written to disk. As hard disks become older, their mechanical components begin to atrophy, increasing the probability and frequency of medium errors on the drive. By comparison, SSDs write data by burning data onto cells within the drive. While these cells can ‘burn out’ over time, making them unusable, the writes to each cell can be accurately measured which in turn makes their burnout rate completely predictable. However, nearly all SSDs today include wear leveling technology within their firmware. Wear leveling takes into account the amount of writes to each cell and intelligently allocates writes between the cells to increase the lifespan of the drive. Between the hardware dependability of SSDs and the software enhancements that complement them, users can generally expect over 5 years’ worth of life from SSDs compared to a standard 3-5 year lifespan of HDDs. When considering the critical nature of database data, the reliability advantages of SSDs over HDDs make them prime candidates to manage the essential applications that most companies rely on every day.

Flash storage is both extremely high performance and highly reliable, making its benefits for database implementations self-evident. However, determining how much flash you need for your databases can be a challenging task. StorTrends has developed a free performance analysis software tool called iDATA that identifies servers within the existing environment, their applications, and their unique performance demands to provide IT administrators with insight into their hardware requirements. You can download the iDATA tool free of charge from the StorTrends website here.