There are also internal considerations like the CPU power of the storage compute engine the storage controller , the efficiency of the storage software and, of course, speed of the storage media installed in the storage system.
If that is the case then transfer rate is essentially the speed at which the storage controller can move a contiguous data block through the storage software to the storage media.
IOPS, however, are different; they are measured as an integer number. It refers to the maximum number of reads and writes to non-contiguous storage locations. Because this positioning of heads is so time-consuming, the importance of storage controller CPU power and the efficiency of storage software are greatly minimized in a hard disk array. Flash arrays virtually eliminate seek time from consideration and as such, they make the other variables like the power of the storage controller and efficiency of the storage software far more important.
The storage controller and storage software can no longer hide behind the bad performance of the hard drive. Flash exposes them for what they are. The first workload requires reading ten MB files, 7. The second workload requires reading ten thousand KB files, the same amount of data, 7. This is an example of how different workloads can require significantly different performance while using the same storage capacity.
IOPS were a far more important measurement in the hard disk array era because the potential number of IOPS was often less than what the data center needed. In the all-flash array era the opposite is true.
Most all-flash arrays will deliver far more IOPS performance than the most data centers will need. The other problem with using IOPS as a way to differentiate between flash storage systems is that there are too many ways to generate an IOPS number, as our illustration above indicates. Even if vendors all standardized on how each of these variables were to be set, it would have little relevance to the data center.
Finally, most data centers are going to have multiple workloads running on their all-flash array. The right way to measure the performance of an all-flash array or even a hybrid array is to develop performance statistics based on particular workloads or a mix of workloads. For example, run a SQL performance test and a VDI performance test at the same time on the same storage system and instead of reporting on IOPS consumed, report on data that is more tangible and relevant to the data center.
In this case, it might be the number of simultaneous SQL users and VDI instances supported while still maintaining acceptable response times. As stated above most all-flash arrays will deliver more performance than most data centers can take advantage of today. Moving data slowly from one system to another reduces performance, but the time it takes for the data to begin moving, when no useful work is being done, is a huge factor in the performance of data storage devices.
There is another aspect of data storage device performance that is at least as important as latency. How many Input or Output IO operations can be performed by the storage device every second, or IOPS , is a very important measure of its performance, and one that is overlooked too often.
Our three main performance areas, how often IOs can occur, how long it takes for an IO task to begin, and the speed of the data transfer into or out of the storage device are simply defined in the computer industry as this:.
The Big 3 throughput, latency and IOPS are what truly indicate the performance capability of a storage device.
Results for the hard drive are shown on the left, while that of the SSD are on the right. Random means the files are scattered all over the drive, not in neat rows or groups, so take more work to find.
Random IO is the most difficult and time consuming type a storage device must deal with. Can performance like this not be noticed by a user?
That eliminates all the overhead involved processing 32 individual commands. I have just purchased my fourth SSD. Though those numbers are improving as we speak. Several of my friends customers are in the process of transitioning now.
The typical consumer will never use the capabilities of SSD. HDD is fast enough, and way cheaper for storage. My only reason for adding SSD to my desktop system, is that I use photo editing programs which can have large swap files on a drive. SSD speeds this up greatly. I cannot say as I agree at all, having installed and transitioned hundreds to SSD personally.
If for start times alone, the consumer wants the increase as much as all others and waiting for that minute and a half startup is now yesterday. People who do experience the SSD for the first time seem to have a whole new appreciation for their system.
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