On Thursday, 2 January 2020 14:43:58 GMT Rich Freeman wrote:
> Out of curiosity, what model drive is it? Is it by chance an SMR / > archive drive? Good catch! I hadn't thought of this - the Linux kernel will need to have DM_ZONED enabled I think, for the OS to manager the shingled writes sequentially, but I don't have this enabled here because AFAIK I have no such drives in my possession. > Due to the limitations on how those write data out I > could see them implementing an internal filesystem that journals > incoming data and then writes it back out after the fact. SMR drives which implement a 'device managed' write mechanism, will use their own firmware to control data storage. The OS would not be aware of anything being different to a conventional drive. > If so then > that might happen even after the kernel thinks it is unmounted. > However, such a drive firmware would probably use a journal that > ensures data is safe even if power is cut mid-operation. The drive > isn't supposed to report that a write is completed until it is > durable. Which I take it to mean the drive would not be unmounted by the OS until it is safe to do so and for all intends and purposes it will also be safe to be powered down thereafter. I would think this would be within seconds of successfully unmounting it. Spinning for 30 minutes or more after it is unmounted sounds excessive to me, if it is only being spun by the firmware for flushing its journal buffers. I have a conventional USB drive (WD passport) which is always spinning whether it is being written to or not. -- Regards, Mick
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