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Benchmark your SSD or hard disk speed
Authored by: bfu.me on Jul 11, '12 07:52:12AM

The read speed test is flawed as written. Using /dev/zero as dd's input and output file doesn't hit the disk at all and will return ridiculous speeds like 15-20 GB/sec. The proper way to do the read test is to be to dd the tstfile created by the write benchmark into /dev/null (but only after clearing the RAM cache by using the "purge" command).

This one-liner will test the write speed, clear the cache, properly test the read speed, and then remove tstfile to reclaim disk space:

dd if=/dev/zero bs=1024k of=tstfile count=1024 && purge && dd if=tstfile bs=1024k of=/dev/null count=1024 && rm tstfile



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Benchmark your SSD or hard disk speed
Authored by: ericswanson on Jul 11, '12 09:15:21PM

Here's what I get using this method (and dividing by 1048576 to get Mb/sec):

Internal laptop hd (7200 rpm, sata): Write=42.99 Mb/sec, Read=38.09 Mb/sec
External G-Raid (esata): Write=134.76 Mb/sec, Read=192.32 Mb/sec
External Seagate hd (laptop drive, USB-2): Write=33.59 Mb/sec, Read=36.38 Mb/sec
External G-Raid (Firewire 800): Write=60.79 Mb/sec, Read=66.17 Mb/sec
Encrypted sparsebundle image on external G-Raid above (esata): Write=68.66 Mb/sec, Read=81.33 Mb/sec



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