From mboxrd@z Thu Jan 1 00:00:00 1970 From: erik quanstrom Date: Tue, 4 Oct 2011 08:17:47 -0400 To: 9fans@9fans.net Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Subject: Re: [9fans] copying fossil filesystem to a bigger disk Topicbox-Message-UUID: 317119fa-ead7-11e9-9d60-3106f5b1d025 > part test7 42249863 44249863 align 7 > term% for (i in /dev/sdC0/test?) { time rc -c 'dd -if /dev/zero -of '$i' -bs 4k -count 250000 >[2]/dev/null' } > 0.57u 8.43s 20.40r rc -c dd -if /dev/zero -of /dev/sdC0/test0 -bs 4k -count 250000 >[2]/dev/null > 0.50u 8.65s 20.71r rc -c dd -if /dev/zero -of /dev/sdC0/test1 -bs 4k -count 250000 >[2]/dev/null > 0.64u 8.44s 20.73r rc -c dd -if /dev/zero -of /dev/sdC0/test2 -bs 4k -count 250000 >[2]/dev/null > 0.60u 8.86s 20.54r rc -c dd -if /dev/zero -of /dev/sdC0/test3 -bs 4k -count 250000 >[2]/dev/null > 0.64u 8.70s 20.77r rc -c dd -if /dev/zero -of /dev/sdC0/test4 -bs 4k -count 250000 >[2]/dev/null > 0.55u 9.00s 20.62r rc -c dd -if /dev/zero -of /dev/sdC0/test5 -bs 4k -count 250000 >[2]/dev/null > 0.48u 8.51s 20.61r rc -c dd -if /dev/zero -of /dev/sdC0/test6 -bs 4k -count 250000 >[2]/dev/null > 0.59u 8.16s 20.78r rc -c dd -if /dev/zero -of /dev/sdC0/test7 -bs 4k -count 250000 >[2]/dev/null > 250000*4096/20.78 = 49 mb/s. this is less than 1/2 the available bandwidth giving the drive lots of wiggle room. and since you're doing sequential i/o the drive can do write combining. - erik