cesar@erotes ~ $ sudo hdparm -tT /dev/sda /dev/sda: Timing cached reads: 12326 MB in 2.00 seconds = 6165.99 MB/sec Timing buffered disk reads: 1426 MB in 3.00 seconds = 474.67 MB/sec
cesar@erotes ~ $ dd if=/dev/zero of=/tmp/testfile1 bs=1G count=1 oflag=direct 1+0 records read 1+0 records written 1073741824 bytes (1,1 GB) copied, 2,44595 s, 439 MB/s
cesar@erotes ~ $ sudo hdparm -W0 /dev/sda /dev/sda: setting drive write-caching to 0 (off) write-caching = 0 (off)
cesar@erotes ~ $ dd if=/dev/zero of=/tmp/testfile2 bs=1G count=1 oflag=direct 1+0 records read 1+0 records written 1073741824 bytes (1,1 GB) copied, 6,9191 s, 155 MB/s
cesar@erotes ~ $ sudo hdparm -W1 /dev/sda cesar@erotes ~ $ dd if=/dev/zero of=/tmp/testfile3 bs=512 count=1000 oflag=direct 1000+0 records read 1000+0 records written 512000 bytes (512 kB) copied, 0,0392862 s, 13,0 MB/s
cesar@erotes ~ $ sudo hdparm -W0 /dev/sda /dev/sda: setting drive write-caching to 0 (off) write-caching = 0 (off) cesar@erotes ~ $ dd if=/dev/zero of=/tmp/testfile4 bs=512 count=1000 oflag=direct 1000+0 registros leídos 1000+0 registros escritos 512000 bytes (512 kB) copiados, 1,63136 s, 314 kB/s