Your mileage may vary, and raid configuration will heavily influence aggregate drive numbers. Search performance will suffer whenever SATA is called upon.
View solution in original post. Keep in mind that the IOPs will vary depending on if they are random or sequential, read or write. For example, the 1TB 7. Sequential read IOPs should be higher due to buffering at the server, adapter, raid card or controller as well as drive. Most drives today have some amount of read cache even some of the lower cost SATA drives. Something else that will impact the IOPs are how much concurrency or activity being sent to the drive, granted the drive has to be able to support the activity.
Otoh, a drive that can support more IOPs may not be being pushed due to how much concurrent work being done. Other factors and considerations include the OS, queue depths, driver config, interface e.
Of course your millage will vary For this reason you must correctly design or choose your storage tier speed in terms of both IOPS and throughput, which rate the speed and bandwidth of the storage respectively. IOPS represents how quickly a given storage device or medium can read and write commands in every second.
Back end IOPS is dependent on the rotational speed of the HD, if applicable solid state drives do not rotate, while traditional hard drive disks do.
The Average Latency in the above formula is the time it takes the disk platter to spin halfway around. It is calculated by dividing 60 seconds by the Rotational Speed of the disk, then dividing that result by 2 and multiplying everything by 1, milliseconds. Of course, for solid state drives, the average latency drops significantly, as there is no rotating disk inside. Therefore you can just plug in 0. More on network issues shortly. Average Seek Time is the time it takes for the head the piece that reads data to reach the area on the disk upon which that data is stored.
The head needs to move around the storage area in order to locate the targeted data. You must average both write and write seek times in order to find the average seek time. Most of these ratings are given to you by the manufacturers. Different applications require different IOPS and block sizes to function properly. A single application may even have different components that function at different size ranges for blocks.
Block loosely translates to any piece of data. File systems write entire blocks of data rather than individual bits and bytes. A file system block can stretch over multiple sectors, which are the physical disk sections. Blocks are abstract representations of the hardware that can or may not be a multiple of physical block size.
Every file takes up one block no matter its size, so choosing the correct block size to efficiently consume storage can make a big difference when it comes to performance. To measure this, do lots of individual tests, with repetitions, and plot the results on a graph: your eyes are better at pictures than at tables of numbers.
And yes, it will be a scatterplot of dots approximating those curves, not nice straight lines ;-. Sign up to join this community. The best answers are voted up and rise to the top.
Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. My workload bottleneck is storage Ask Question. Asked 7 years, 8 months ago. Active 7 years, 8 months ago. Viewed 6k times. Improve this question. Totor Totor 2, 3 3 gold badges 21 21 silver badges 30 30 bronze badges. I'm not sure how we can even hope to answer without knowing what services you're trying to run, how many users, etc Is that better for you?
Add a comment. Active Oldest Votes. I hope this helps, I know it's not as simple an answer as you were hoping for. Improve this answer. Basil Basil 8, 3 3 gold badges 36 36 silver badges 73 73 bronze badges.
Actually, I was not really hoping for a simple answer like edvinas. I would have liked to know how to measure my need i. In your situation, it's impossible to accurately measure your need for IOPS, so I don't have much choice. Generally speaking, any workload that is IOPS bound will be best served by SSD, but that's actually a pretty rare circumstance small transactional databases, for example.
Under what situation would it have been possible to "accurately measure my need for IOPS" then? For example; if you're looking at changing storage and you're not currently storage bound, or if you're upgrading or changing the application in a way that you know the percent increase of IOPS it'll require and you're not currently storage bound.
In general, though, if you are storage bound, the only quantifiable answer you can give is "something more than we currently get". Everything after that is guesswork. If you're interested, I could go on at length about variously accurate ways to estimate your requirements
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