On Thursday, 4 January 2024 02:48:13 GMT Adam Carter wrote: > > > dd if=/path/to/iso-image of=/dev/sd? bs=4M status=progress > > > > > > Replace the obvious bits. > > > > I've tried a few values of block size over the years, but so far I haven't > > noticed any difference. I haven't run any proper tests though. > > I think it's just that the default blocksize is (or was) very small (512 > bytes?) so setting it to anything non-small helps a lot. > > eg one example (from > https://superuser.com/questions/234199/good-block-size-for-disk-cloning-with > -diskdump-dd#234204) seems to show that most gains are in by around 16k. > There's probably a lot of testing noise in these results. > > $ ./dd_obs_test.sh > block size : transfer rate > 512 : 11.3 MB/s > 1024 : 22.1 MB/s > 2048 : 42.3 MB/s > 4096 : 75.2 MB/s > 8192 : 90.7 MB/s > 16384 : 101 MB/s > 32768 : 104 MB/s > 65536 : 108 MB/s > 131072 : 113 MB/s > 262144 : 112 MB/s > 524288 : 133 MB/s > 1048576 : 125 MB/s > 2097152 : 113 MB/s > 4194304 : 106 MB/s > 8388608 : 107 MB/s > 16777216 : 110 MB/s > 33554432 : 119 MB/s > 67108864 : 134 MB/s
Interesting. I think I'll stick to my usual 64MB block size. -- Regards, Peter.
