Hi Thomas, You may not be getting an accurate picture of your sustained write throughput using dd. Since you are using ext4, I'm assuming you are using Linux :-) Linux does a good job caching to RAM before writing to disk, so when you write only 1GB using dd, you are mostly exercising your RAM (assuming you have a normal amount of RAM). If you run a test writing a file much larger than your RAM, you should see something closer to your true sustained write speed.
For example, I get the following results running your test, which make this caching very obvious: [ Desktop]$ dd if=/dev/zero of=/home/amadsen/test.bin bs=10K count=100000 100000+0 records in 100000+0 records out 1024000000 bytes (1.0 GB) copied, 2.62228 s, 391 MB/s If I increase the amount by a factor of 10, the system is forced to actually write to disk finally and the throughput falls: [Desktop]$ dd if=/dev/zero of=/home/amadsen/test.bin bs=100K count=100000 100000+0 records in 100000+0 records out 10240000000 bytes (10 GB) copied, 77.4247 s, 132 MB/s Here is a site I use for checking out drive performance, there is a lot of difference between different SSDs. http://www.tomshardware.com/charts/ssd-charts-2010/Fresh-state-Throughput-Write-Average,2314.html Good luck! Aaron http://www.epiq-solutions.com/
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