I/Os Are Not Created Equal — Random I/O vs. Sequential I/O
Random I/O Always Outperforms Random I/O on Hard Disk Drives or SSDs
Accessing data randomly is much slower and less efficient than accessing it sequentially. Simply, it is faster to write/read the same data with a single sequential I/O rather than multiple, say 25, smaller random I/Os. For one, the operating system must process all those extra I/Os rather than just the single one, a substantial overhead. Then, the storage device also has to process all those multiple I/Os too.
With Hard Disk Drives (HDDs), the penalty is worse because the extra disk head movement to gather the data from all those random I/Os is very time-consuming. With Solid State Drives (SSDs), there is not the penalty of the disk head movement, just the penalty of the storage device having to process the multiple I/Os rather than a single one. In fact, …
Read on to find out more about how Sequential I/O always outperforms Random I/O on hard disk drives or SSDs.
