4 ms·
It was explained to me back in the stone age that one did 3 syncs because disks were slow enough that if you did one sync all the buffers might not be flushed b
by kjs3 4y ago
It was explained to me back in the stone age that one did 3 syncs because disks were slow enough that if you did one sync all the buffers might not be flushed before the reboot took hold. So do 3 syncs to make sure. Borking a filesystem wasn't fun.
Not saying it's correct, and it's still a habit for me.
- somesortofsystm 4y ago"One sync tells the system to flush all i/o buffers, the second one serves to ensure the buffers are sync'ed, and the third is useful in case slow-quitting processes meanwhile even still have things to flush before letting go of a node, and then of course .. ;reboot .. " Yeah, but it also means, if done in rapid succession (i.e. one shell cmd "sync;sync;sync", it can tell the machine on the other end of the i/o to do 'special' operations, such as rewind tape, settle card tray intake, etc. Long-forgotten aspects of operation which neverless fit in the 'class' of action, where data is settled and made safe.