Is it recommended to defragment SMR disks? Or is it redundant because the drive's firmware manages tracks on its own? If it does that. I ask because there are plenty of ambiguities surrounding just what the firmware does in an SMR. CMR is straightforward and these disks generally put the data where the filesystem says to. But with SMR? Who knows?
I'm sure that's sound advice. But the original questions remain undiscussed. Is it recommended to defragment SMR disks? Or is it redundant because the drive's firmware manages tracks on its own? If it does that. Furthermore, since SMR is usually TRIM-enabled I would suspect they organize their tracks differently from the filesystem.
@Keatah is correct about internal track organization. You can view an SMR disk just like an SSD as far as fragmentation is concerned with one very big caveat. SMRs will reorient their internal storage as the OS offers TRIM commands, following DATA block usage and deallocation, for purposes of cleaning up DATA (garbage collection) and re-alignment (as in defragmentation). The big difference is that in an SMR disk, this can be very time consuming (remember, this is a platter based disk with a mechanical positioner, not a solid state NAND block manager). As a result, internal mgmt (garbage collection) of a SMR can be time consuming and slow that device down, taking bandwidth away from the System and the OS. Recommendations have been made by SMR manufacturers as far as when to TRIM and how much at one time... I don't even know if any of those recommendations have been implemented yet at the OS level. Here's a Western Digital WHITE PAPER that tries to discuss these many issues (benefits vs drawbacks). https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/product/internal-drives/wd-purple-hdd/whitepaper-generic-benefit-for-hard-disk-drive.pdf
...and I would like to add, it's not clear at all whether the SMR internal re-orientation of its DATA also provides the DATA access protection that SSDs do when they set their TRIMmed block data to a pre-determined (all ZEROs or all ONEs) value or a RANDOM value following TRIM. It seems to me that would be a very expensive operation (rotational positioning) for a Magnetic storage device with a mechanical positioner... way more so than just defragging underlying DATA.
