Can't be of many help on this forum (yet), because im a noob on music, but that is IT , and on there yes, i have enough knowledge to give some advice.
Basically there are many methods for storing information (optical, tape drive, etc) , in this case, we are discussing about two, magnetic based (HDD) and memory based (SSD / USB Stick).
fragmentation is an empty space between 2 files, that later is filled with part of another file, then the file is fragmented in at least 2 parts, the empty space betwen that 2 files, and another free space of the media... if you have luck, that file will only splitted in two... usually is splitted in MANY parts.. 20 or even more more, that free space is created when you, (or the operating system/program) removes a file, so a free space is created on the media, of the size of that file, (sectors in a magnetic HDD , memory cells on a memory based media)
The fragmentation of files occurs in both of them (, BUT , is not reccomended to defrag at all to do so on memory based media, as already many told you. thats the shord story , "Dont do it", the little more lenghty why:
On a magnetic HDD, you have a mechanical head that moves over a disk (like the old vinyls), so, when you have file that is splitted (fragmented) all over the magnetic surface of the disk, the HEAD has to move all over the surface of the disk to read that files (the files are stored in a large string like method, think on a train, with wagons, each wagon is a sector, so, if you have all the wagons you need (for assembling the train) one after another , on the same track, you can assemble the train very fast and dispatch it ... if some of the wagons you need for assembling the train, are on different tracks... well.. and imagine assembling a train with wagons on 20 or 30 different tracks .... quite some time will pass until you can dispatch that train ) , the same occurs on the HDD, the Disk must "assemble"the sectors, before dispatching the file to the Operating system... luckily is faster to search sectors to ensable that wagons on trains...
That head moves over the disk at glazing speeds, 100 times per second or more, BUT is mechanical, so it actually MOVES over the disk looking for those sectors... normally takes around 17 to 25 mS (0,017/0,025) seconds... its pretty fast BUT, when you have many sectors "scattered" around the disk plates... time gets added pretty quick!! the transfer time, from the plate, to the computer memory is almost negligible in comparison to the 25mS the head takes to move.... when a file is NOT fragmented , that times decreases to only 6 mS usually , so is at least 3 times faster (thats why , after you defragment a HDD based PC, you feel and makes your computer "faster"
On the memory based storage, you dont have any mechanical parts, they're only electrons moving around , so as the transfer times "over the wire" from the media to the Operating System are practically the same that for magnetic HDDs, and you dont have to "wait" 6 mS or more for that head moving each time (a file fill many many sectors usually, think on a very verry long train) that SSD are pretty much "faster" that the mechanical one.
The problem in this case, is that each cell of memory inside your SSD or USB stick, supports a LIMITED amount of reads, and much much lower amounts of WRITES, thats why you DONT defrag a memory based media, you must move (read & write) memory cells around the media, and you shorten the life expentancy ouf your media, sometimes drastically, with no actual beneficts at all, is exactly the same (for the SSD) read memory cells , one after another, or scattered around!!
SSD have "reserved" empty space , (that you cant see), for replacing "dead" memory cells, (its called provisioning space) but that space has a limit , and when the disk runs out of provisioning cells... you start to have problems... memory that can't be written anymore, or whorse , that can't be READ anymore, so you lose the file that that cell has a part of it
On the SSD theres a funcion to "replace" the defrag command, its called TRIM... but you dont need that , all modern operating systems do that by itselves on SSDs
Sorry for the lenghty explanation, but i like to explain WHY things occurs, not tell : "do that because i said so" ... thats a method i use when i lost my temper with a customer XD
