>>> Are SSD drives still subject to SMR ? I've thought that it >>> was related only to magnetic drives not on SSD. Indeed SMR is a magnetic recording technique that potentially results in very expensive read-modify-write operations. > And the warning really is outdated. What matters is that the > HDD needs to support TLER (ie scterc capabilities) SCT/ERC/TLER is indeed an important feature in case HDD fail *and* long latencies (like 30-100s) are not a good idea. Most SSD either have SCT/ERC/TLER or don't need it as their retry cycles are very short. What matters more is setting the Linux driver retry timeout (which ought to be must always be higher than that of the drive) SSDs can have different issues that are undesirable for most "business" applications, usually: * Volatile write buffers (lack of "Power Loss Protection"). * Low endurance (low Device Writes Per Day). * Potential high latencies in mixed workloads (interleaved read and write streams). * Long term reduction in data transfer rates because FTL "compaction" cannot run faster than erase block fragmentation. These can all affect an MD RAID set, in particular if bitmaps or write logs are used or if the workload is challenging.
