# dd bs=1M count=1024 if=/dev/zero of=test conv=fdatasync
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 3.7375 s, 287 MB/s
# hdparm -tT /dev/disk/by-label/DOROOT
/dev/disk/by-label/DOROOT:
Timing cached reads: 16394 MB in 2.00 seconds = 8205.62 MB/sec
Timing buffered disk reads: 868 MB in 3.00 seconds = 289.17 MB/secI upgraded some of my VMs and they all failed to boot on their own and I had to manually boot each one after the migration.
[root@server ~]# dd bs=1M count=1024 if=/dev/zero of=test conv=fdatasync
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 6.29244 s, 171 MB/s 287 MB/sec / $5 ~ 57 MB/sec/dollar
816 MB/sec / $20 ~ 40 MB/sec/dollar 287 MB/sec / $20 ~ 14 MB/sec/dollar
I don't think MB/sec/dollar makes sense simply because disk speed does not scale. If you need a (very) fast disk, Linode is obviously the better choice.1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB) copied, 62.9023 s, 17.1 MB/s
$ dd bs=1M count=1024 if=/dev/zero of=test conv=fdatasync 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB) copied, 5.83509 s, 184 MB/s
dd bs=1M count=1024 if=/dev/zero of=test conv=fdatasync
1024+0 records in
1024+0 records out
1073741824 bytes (1,1 GB) copied, 13,6791 s, 78,5 MB/s
hdparm -tT /dev/xvda
/dev/xvda:
Timing cached reads: 3580 MB in 2.00 seconds = 1794.00 MB/sec
Timing buffered disk reads: 336 MB in 3.01 seconds = 111.75 MB/sec $> dd bs=1M count=1024 if=/dev/zero of=test conv=fdatasync
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 2.19598 s, 489 MB/s
$> hdparm -tT /dev/xvda
/dev/xvda:
Timing cached reads: 12446 MB in 1.98 seconds = 6273.29 MB/sec
Timing buffered disk reads: 1768 MB in 3.00 seconds = 589.00 MB/sec dd bs=1M count=1024 if=/dev/zero of=test conv=fdatasync
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 2.17496 s, 494 MB/s
hdparm -tT /dev/xvda
/dev/xvda:
Timing cached reads: 18560 MB in 1.98 seconds = 9358.78 MB/sec
Timing buffered disk reads: 2510 MB in 3.00 seconds = 836.61 MB/sec` $ dd bs=1M count=40960 if=/dev/zero of=test conv=fdatasync
40960+0 records in
40960+0 records out
42949672960 bytes (43 GB) copied, 48.455 s, 886 MB/s(Okay Linode, you've finally done it. I'll get rid of my oddball $30/mo plan sometime soon. That extra $10 used to get me a necessary 180MB of extra RAM!)
dd if=/dev/zero of=test bs=512 count=1500 oflag=dsync
I'm getting "6.40264 s, 120 kB/s" on my laptop's SSD, but on a proper server with a RAID card and cache enabled I get "0.187033 s, 4.1 MB/s".
$ dd if=/dev/zero of=test bs=512 count=1500 oflag=dsync
1500+0 records in
1500+0 records out
768000 bytes (768 kB) copied, 0.427272 s, 1.8 MB/s $ dd if=/dev/zero of=test bs=512 count=1500 oflag=dsync
1500+0 records in
1500+0 records out
768000 bytes (768 kB) copied, 1.64471 s, 467 kB/s 1500+0 records in
1500+0 records out
768000 bytes (768 kB) copied, 1.17399 s, 654 kB/s768000 bytes (768 kB) copied, 0.45329 s, 1.7 MB/s
Old cpuinfo model: Intel(R) Xeon(R) CPU L5520 @ 2.27GHz
CPUs compared: http://ark.intel.com/compare/75277,40201