There is "seek time" in SSDs, just as there is "seek time" in RAM. It's just orders of magnitude faster.
Some of the principles remain the same across disk, SSD and RAM. Sequential access is usually faster than random ("seek") access.
Seek time from a storage point of view just means the lookup latency - the cost of jumping to a random source of data (an area on disk or in memory or in another datacenter). You could think of a hash table lookup as "seek time". It could be attributed to an L1/L2 cache reference, main memory reference, physical disk seek or network roundtrip etc.
Just because the concept of "seek time" originated with spinning rust does not mean it must remain there.
No there is no seek time in SSDs at all, there is simply a constant latency. And no RAM does not have seek times either. The term "seek" is not some loose and fungible term that can be applied to different subsystems.
A seek is an agreed upon industry concept. A seek is composed of the following components[1]:
• start-up: the arm is accelerated, typically with constant torque (force) until it reaches half of the seek distance, or a fixed maximum velocity;
• coast: for a long seek, the arm will be allowed to coast across most of the distance at its maximum speed;
• slowdown: the arm is brought to rest, hopefully exactly on top of the desired track;
• settle: the disk controller uses servo positioning information to fine-tune the position of the head over the desired track on the selected surface.
Additionally a write seek takes slightly longer than a read seek on a rotating disk, this is because of settling described above. This has no corollary in SSDs.
Rotating disks also have something known as an Average latency which is calculated as the time it takes for the sector of the disk being accessed to rotate into position under a read/write head. The reason I bring this up is because seek and latency are two distinct measurements on mechanical disks and it is the latency measurement which could be applied to SSDs as it is a constant, it mechanical disk this would be gated on the rotational speed of the disk(RPMs)but this is a constant.
And the reason this all matters is that
in order to calculate the average IOPS on a mechanical disk you use the following formula:
Divide 1 by the sum of the average latency in ms and the average seek time in ms (1 / (average latency in ms + average seek time in ms).
This formula is obviously meaningless in the context of SSDs.
And average seek time is also well understood to mean:
The average of all possible seek times which technically is the time to do all possible seeks divided by the number of all possible seeks, but in practice it is determined by statistical methods or simply approximated as the time of a seek over one-third of the number of tracks. This formula goes back to IBM and the Winchester drives I believe.
So no in SSDs there is no such thing as a seek. There is simply a latency and that latency is a constant.
Some of the principles remain the same across disk, SSD and RAM. Sequential access is usually faster than random ("seek") access.
Seek time from a storage point of view just means the lookup latency - the cost of jumping to a random source of data (an area on disk or in memory or in another datacenter). You could think of a hash table lookup as "seek time". It could be attributed to an L1/L2 cache reference, main memory reference, physical disk seek or network roundtrip etc.
Just because the concept of "seek time" originated with spinning rust does not mean it must remain there.
See: https://gist.github.com/jboner/2841832