我发了一下VPS的DD数据，[root@myvps ~]# dd if=/dev/zero of=test bs=64k count=4k oflag=dsync
4096+0 records in
4096+0 records out
268435456 bytes (268 MB) copied, 708.024 seconds, 379 kB/s
!!!!复制代码下面是回复：
By using such a small block size, large count and oflag=dsync you're doing nothing but crippling the drive's write cache, which you'd never normally want to do, and that would make the test completely irrelevant to real-world performance. This is not relevant to real world use at all.
You're using a command that forces the disk to write individual 64K blocks to disk, bypassing all write caching. Any disks that report 10 MB or more on that command are either SSD drives or on a hardware raid that ignores the flag to disable write caching.
Again, the correct command to actually get more of an accurate figure when it comes to real-world performance/usage would be: dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
This command is heavily used throughout the VPS market, but if you are looking for something more accurate, you should definitely use ioping.
求翻译，神马意思？？？翻译
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