Subj : Re: Move bookworm system from SSD to NVME To : The Natural Philosopher From : Richard Kettlewell Date : Sat Aug 03 2024 10:02:07 The Natural Philosopher writes: > On 02/08/2024 15:03, Björn Lundin wrote: >> dd'ing 500 Gb to an ssd disk, I've seen sync taking 30 s or more >> and sync is of course started AFTER dd is done >> So - how do you know it is done its internal business? >> Not all drives have blinking LEDs >> sync makes it easy to know > > Even sync may not be enough. > SSDS/NVM have their own internal caching. The sync syscall (and command) will flush those too. Unless you’ve paid extra for a drive with a huge cache I would expect the extra delay while the on-drive cache is flushed to be absolutely tiny in human terms, and certainly tiny compared to flushing the OS’s cache, which can be multiple gigabytes. References: * https://www.kernel.org/doc/Documentation/block/writeback_cache_control.txt * https://linux.die.net/man/2/sync * https://github.com/torvalds/linux/blob/master/fs/sync.c#L87 -- https://www.greenend.org.uk/rjk/ --- SoupGate-Win32 v1.05 * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3) .