- Faster RAID rebuilds/resyncs through tuning of drive firmware and DSM behavior.
- Reduced risk of drive dropouts during rebuilds by coordinating error-recovery behavior between the drive firmware and the NAS
So, Synology's Quick Repair essentially handles the top two points, and it works on all the other drives, too. The one thing missing to fulfill that promise is the ZFS file system, which Synology does not offer us. Perhaps something is on the verge of being announced.
- More predictable handling of bad sectors and read errors during rebuild operations.
The simple trick of merely shortening the wait time for a read error won't improve matters. But it will certainly lead to higher sales figures.
- Better validation of drive firmware with Synology’s storage stack, resulting in fewer unexpected compatibility issues.
That sounds logical, assuming the NAS operates exclusively using its own hard drive firmware. Arrangements were made for that.
The aim is to suggest to the customer that the fear of total data loss during recovery can be eliminated simply by using the manufacturer's own drives.
However, this works much better with ZFS, and ideally only with a mirrored drive setup. With Btrfs, the RAID metadata is simply located too close together. Fragmenting the data across many hard drives in a RAID 5 configuration is absolutely counterproductive, not only in terms of the time required but also regarding the level of risk. The more drives involved in the recovery process, the greater the risk of total failure, and the longer the period of anxious suspense. Simply using hard drives with perceptibly different runtimes helps, too.
If redundancy data is corrupted during hardware recovery, recovery is certainly impossible; even specialized drive firmware won't help in that case.
Only ZFS can handle advanced self-healing and also address bit-flipping issues.