Drive performance changes on the HDDs platters as the head moves towards the centre (angular velocity). Slow read times are the result of data fragmentation (latency) and the need to move the actuator arm between positions. Its not easy to keep data contiguous and make changes too... Generally speaking, as the fill rate increases the performance is reduced (outer tracks are used up). Some drives support zone bit recording to help with this. You can do things to offset performance characteristic on HDDs. One of the common ones was to make sure you put the key data in the first partition sat over the outer tracks, then make sure the less important/performance data requirements are in the last partitions.
HDDs are obsolete now unless you have a requirement to store lots of data for extended periods of times (NLS) or have a workload that is sequential in nature.
SSD have very low and linear seek times - no moving parts.
What people get confused around SSDs is how the data is actually stored and the way the blocks work. SSDs struggle to use left over space in part used blocks, but manufactures get around this by shipping more capacity than your are buying. SSDs also have a garbage collector to help manage part used blocks too. My rule of thumb for SSDs is 65-70 is the tipping point.
HDDs are obsolete now unless you have a requirement to store lots of data for extended periods of times (NLS) or have a workload that is sequential in nature.
SSD have very low and linear seek times - no moving parts.
What people get confused around SSDs is how the data is actually stored and the way the blocks work. SSDs struggle to use left over space in part used blocks, but manufactures get around this by shipping more capacity than your are buying. SSDs also have a garbage collector to help manage part used blocks too. My rule of thumb for SSDs is 65-70 is the tipping point.
