Re: external USB disk: 400MB/s transfer, but get only 40MB/s
- In reply to: Jin Guojun[VFF]: "Re: external USB disk: 400MB/s transfer, but get only 40MB/s"
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Date: Thu, 29 Jan 2026 23:42:14 UTC
On 1/29/26 15:12, Jin Guojun[VFF] wrote: > ... snapped > > You may try using different USB ports on different computers, testing > UFS file systems or even using a raw disk by shrinking the NTFS > partition and creating a new empty slice like p2 (dd if=/dev/zero > of=/dev/da0p2). Be aware that the inner disk transfer rate can be much > slower than the outer disk tracks. > In your R/W tests, the reading test is accessing on the very outer tracks. If the NTFS file system is nearly full, the writing test is writing to inner tracks. You can test the inner reading speed by using skip=#### in dd command. dd if=/dev/da0 of=/dev/null bs=1m skip=800k # for 1TB drive dd if=/dev/da0 of=/dev/null bs=1m skip=1800k # for 2TB drive, etc This may provide more information on drive performance and test results. Best, -Jin