~
is local, ~/htdocs
mounted by vboxsf, /var/htdocs
mounted by nfs.
root@Ubuntu:~# time dd bs=8k count=300000 if=test of=/dev/zero 300000+0 records in 300000+0 records out 2457600000 bytes (2.5 GB) copied, 3.9852 s, 617 MB/s real 0m3.990s user 0m0.004s sys 0m2.794s
root@Ubuntu:~# time dd bs=8k count=300000 if=/dev/zero of=test conv=fdatasync 300000+0 records in 300000+0 records out 2457600000 bytes (2.5 GB) copied, 3.87739 s, 634 MB/s real 0m3.890s user 0m0.032s sys 0m3.501s
it takes too long, give up.
root@Ubuntu:~# time dd bs=8k count=300000 if=/dev/zero of=/var/htdocs/test conv=fdatasync 300000+0 records in 300000+0 records out 2457600000 bytes (2.5 GB) copied, 146.354 s, 16.8 MB/s real 2m26.361s user 0m0.040s sys 0m3.493s
root@Ubuntu:~# time dd bs=8k count=300000 if=~/htdocs/test of=/dev/zero 300000+0 records in 300000+0 records out 2457600000 bytes (2.5 GB) copied, 28.0652 s, 87.6 MB/s real 0m28.068s user 0m0.012s sys 0m15.446s
root@Ubuntu:~# time dd bs=8k count=300000 if=/dev/zero of=~/htdocs/test conv=fdatasync 300000+0 records in 300000+0 records out 2457600000 bytes (2.5 GB) copied, 45.8428 s, 53.6 MB/s real 0m45.846s user 0m0.020s sys 0m22.363s