On Sat, Aug 22, 2020 at 04:15:38AM +0000, Caveman Al Toraboran wrote: > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Saturday, August 22, 2020 12:10 AM, Grant Taylor > <gtay...@gentoo.tnetconsulting.net> wrote: > > > There is some nebulous area around what that actually means. But the > > idea is that the receiving server believes, in good faith, that it has > > committed the message to persistent storage. Usually this involves > > writing the message to disk, probably via a buffered channel, and then > > issued system calls to ask the OS to flush the buffer to disk. > > just to double check i got you right. due to > flushing the buffer to disk, this would mean that > mail's throughput is limited by disk i/o? > > or did i misunderstand? > > i sort of feel it may suffice to only save to > disk, and close fd. then let the kernel choose > when to actually store it in disk.
When an M.T.A. encounters mail, the content of the mail will first exist in the M.T.A.'s local memory, in a buffer. Before sending an "OK" to the sending server, it should first make an attempt to write it to disk, through an fwrite (stdio) or write (POSIX) call. At that point, it is, in theory, the kernel's choice if and when it is _actually_ written to disk, but if one of the aforementioned functions return a success code, the M.T.A. has done its bit, and can consider the message "safely stored". -- Ashley Dixon suugaku.co.uk 2A9A 4117 DA96 D18A 8A7B B0D2 A30E BF25 F290 A8AA
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