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Path: ...!weretis.net!feeder9.news.weretis.net!feeder8.news.weretis.net!news.nntp4.net!nntp.terraraq.uk!.POSTED.tunnel.sfere.anjou.terraraq.org.uk!not-for-mail From: Richard Kettlewell <invalid@invalid.invalid> Newsgroups: comp.sys.raspberry-pi Subject: Re: Move bookworm system from SSD to NVME Date: Sat, 03 Aug 2024 10:02:07 +0100 Organization: terraraq NNTP server Message-ID: <wwvsevmvv1s.fsf@LkoBDZeT.terraraq.uk> References: <v8cqd6$1gdnp$1@dont-email.me> <v8e73l$1o2dm$1@dont-email.me> <v8frll$24ic1$1@dont-email.me> <v8ft4f$250uj$1@dont-email.me> <v8gamm$28554$1@dont-email.me> <20240801171000.46ce321a2dd0cb03be7cba00@eircom.net> <v8ghss$290sp$1@dont-email.me> <20240801192923.a827ba8d22853e9bc6c5cfb3@eircom.net> <v8gm3e$2atj2$1@dont-email.me> <v8go75$2bmb1$1@dont-email.me> <v8i9jp$2oohc$1@dont-email.me> <v8ikp3$2qqdd$2@dont-email.me> <v8ip08$2ralv$1@dont-email.me> <v8iph9$2rqib$2@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: innmantic.terraraq.uk; posting-host="tunnel.sfere.anjou.terraraq.org.uk:172.17.207.6"; logging-data="124468"; mail-complaints-to="usenet@innmantic.terraraq.uk" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) Cancel-Lock: sha1:KYT0vMZFHagmpU/gfPKU9BTQSfQ= X-Face: h[Hh-7npe<<b4/eW[]sat,I3O`t8A`(ej.H!F4\8|;ih)`7{@:A~/j1}gTt4e7-n*F?.Rl^ F<\{jehn7.KrO{!7=:(@J~]<.[{>v9!1<qZY,{EJxg6?Er4Y7Ng2\Ft>Z&W?r\c.!4DXH5PWpga"ha +r0NzP?vnz:e/knOY)PI- X-Boydie: NO Bytes: 2544 Lines: 24 The Natural Philosopher <tnp@invalid.invalid> 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/