SSDs generally read at the page level, so you can get full performance or close to it from much smaller reads than 256KB or more. For example, you may be able

SSDs generally read at the page level, so you can get full performance or close to it from much smaller reads than 256KB or more. For example, you may be able get maximum performance from 4K or 8K byte reads. Of course, there are a few layers between you and the SSD so you have to make sure you have the SSD actually sees enough pending requests at all times for maximum performance. If you just read one 4K block before submitting the next one, you'll get terrible performance because at queue depth of 1 the SSD is utilized most of the time (i.e., the bandwidth delay product is much lager than 4096 bytes). This effect can lead the erroneous conclusion that small block sizes are slow when queue depth is actually the confounding factor (large blocks effectively feed many page-sized read requests to the SSD at once, so you can get away with a lower queue depth). Writes are different but you also don't need gigantic block sizes. For SSDs available as EC2 local storage, for example, a 4K random write load can extract full performance if you get the other parameters right.