SMR is such a horrible backwards "technology", I wonder why vendors still push it aggressively on users after all these years.
1. Its performance is noticeably worse than CMR.
2. The density increase SMR provides compared to CMR is not that much. It's 25% at most.
3. SMR is not a separate evolutionary path that can be developed further to have increasingly more density compared to CMR. It is more like a variation of the same technology which provides slightly more density in exchange for serious disadvantages. SMR and CMR both directly depend on, and benefit from developments in platter densities. When a new, denser platter generation is introduced, CMR and SMR benefit from it same.
4. A huge portion of the drive must be reserved as a non-SMR cache area to mitigate the performance penalty SMR brings. Notice that this is an extra area that does not exist on a CMR drive so it reduces density increase SMR brings.
5. SMR drives have much larger DRAM cache to mitigate the performance penalty (64MB on a CMR drive vs 256MB on SMR drives), increasing the cost for that part.
6. Logic and mechanism of writes are much more complicated on a SMR drive than a CMR one. Drive is separated into different zones, data must be stored on a cache zone, then new data should be written into permanent zones in an optimal manner in background during idle time, managing different zones, cache area, rewrites, background tasks etc. all these makes the drive firmware much more complicated. Compared to a SSD firmware it is actually worse of both worlds: You're getting all the complexity of a SSD firmware with a worse performance than a regular hard drive.
7. What is even more worrying than those technical details are that vendors are sinking more and more resources and pushing very hard on technologically dead-end SMR technology. WD even wrote a PR piece called a "Zoned storage initiative" for trying to paint host managed SMR technology the future of storage and developed a linux filesystem called zonefs to back it up.
8. Despite all those shortcomings, they don't even sell SMR drives cheaper than CMR drives.
TL;DR: SMR is a harmful technological "drug" HDD vendors use to buy at most few years of time in platter density but with a very serious side effects.
I wish they were. They're actively pursuing it while discontinuing CMR. 5 years ago 1TB CMR laptop drives were abundant. Nowadays you'd be hard pressed to find a non-SMR one.
1. Its performance is noticeably worse than CMR.
2. The density increase SMR provides compared to CMR is not that much. It's 25% at most.
3. SMR is not a separate evolutionary path that can be developed further to have increasingly more density compared to CMR. It is more like a variation of the same technology which provides slightly more density in exchange for serious disadvantages. SMR and CMR both directly depend on, and benefit from developments in platter densities. When a new, denser platter generation is introduced, CMR and SMR benefit from it same.
4. A huge portion of the drive must be reserved as a non-SMR cache area to mitigate the performance penalty SMR brings. Notice that this is an extra area that does not exist on a CMR drive so it reduces density increase SMR brings.
5. SMR drives have much larger DRAM cache to mitigate the performance penalty (64MB on a CMR drive vs 256MB on SMR drives), increasing the cost for that part.
6. Logic and mechanism of writes are much more complicated on a SMR drive than a CMR one. Drive is separated into different zones, data must be stored on a cache zone, then new data should be written into permanent zones in an optimal manner in background during idle time, managing different zones, cache area, rewrites, background tasks etc. all these makes the drive firmware much more complicated. Compared to a SSD firmware it is actually worse of both worlds: You're getting all the complexity of a SSD firmware with a worse performance than a regular hard drive.
7. What is even more worrying than those technical details are that vendors are sinking more and more resources and pushing very hard on technologically dead-end SMR technology. WD even wrote a PR piece called a "Zoned storage initiative" for trying to paint host managed SMR technology the future of storage and developed a linux filesystem called zonefs to back it up.
8. Despite all those shortcomings, they don't even sell SMR drives cheaper than CMR drives.
TL;DR: SMR is a harmful technological "drug" HDD vendors use to buy at most few years of time in platter density but with a very serious side effects.