My rMBP 15" is acting funny in that when attaching a Samsung 830 128GB SSD directly to the laptop's two USB 3.0 ports sequentially, I will randomly have transfer speeds of either under 50 GPS or over 200 GPS. Any thoughts?
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rMBP 15" - Two USB 3.0 ports, 2 different transfer speeds
- Thread starter foto-max
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simsaladimbamba
Guest
How do you measure the transfer rate and can you tell us what kind of unit "GPS" is? Transfer rates are either measured in Bits per second (bps or b/s) or Bytes per second (Bps or B/s), thus you should report it in either xy Megabit/s (Mbps or Mb/s) or xy MegaByte per second (MBps or MB/s).
get blackmagic disk speed test from the app store.
it will give you the most consistant numbers, and provides a good benchmark when comparing multiple situations.
it will give you the most consistant numbers, and provides a good benchmark when comparing multiple situations.
Sorry, had a little too much caffeine this am. The speeds I quoted are of course Mbps and were obtained with Blackmagic.
simsaladimbamba
Guest
If they were Mbps then it would be under 6.25 MB/s or over 25 MB/s. But I guess you experienced 50 MB/s and 200 MB/s.
You could also try these:
simsaladimbamba
Guest
One port reports 50 MB/s and less, and port reports 200 MB/s and more?
Maybe it has something to do with power?
The laptop is continuously on ac power. It has been rebooted a number of times without effect. All OS and programs are currently up to date.
lederermc
macrumors 6502a
My (old) understanding is that Unix uses otherwise free memory as file buffers. The first time you run a test a given file is read/written from/to actual disk. The seconds time it may be in central memory. As mention by waw74, black magic speed tester propably would not be affected by this.
