Test your total disk IO capacity, regardless of caching, to find out how fast the TRUE speed of your disks are
1+0 records in 1+0 records out 268435456 bytes (268 MB) copied, 1.50648 seconds, 178 MB/s real 0m7.119s user 0m0.002s sys 0m0.649s
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Let dd use direct I/O to write directly to the disk without any caching. You'll encounter very different results with different block sizes (try with 1k, 4k, 1M, ... and appropriate count values).
0time dd if=/dev/zero of=blah.out oflag=direct bs=256M count=1
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Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?
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hdparm -t /dev/sdathis will test drive throughput by actually streaming a write off the disk. Use the -T option to test how fast the cpu, memory, & linux disk buffer cache can theoretically go. The underlying filesystem cansync; time { dd if=/dev/zero of=test bs=256m count=1; sync; }