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I'm using a 2.5" SATA disk, via an enclosure for eSATA on my laptop. It came with a USB powered adapter, which has two USB ends.
Since I don't have an eSATAp port, I need the power from the USB plugs, but I noticed that it works with either one or both plugged in.
Are there any advantages or disadvantages in using a single USB power or both? I imagine that if it didn't get enough power, it would simply not work.
I have not noticed any performance degradations, and I would really like to utilize the extra USB port.
Also, does this apply to USB powered USB to SATA enclosures/disks?
edit Since this not easy to answer generically, i'll ask specifically for my ST9500420AS drive, connected via either 1x USB 2.0 or 2x USB 2.0 slots, running under eSATA.
edit with bounty Layman terms: If it works with 1 USB cord and with 2 USB cords, does that mean that it will work slower with 1 cord? Or does it mean that since it's on, it's working at full capacity?
benchmark results Thanks to the answers, indeed 1 USB is enough if it manages to work.
Here are my benchmark results:
CrystalDiskMark 3.0.2 x64
1 USB for Power
Sequential Read : 83.832 MB/s
Sequential Write : 78.545 MB/s
Random Read 512KB : 29.415 MB/s
Random Write 512KB : 35.368 MB/s
Random Read 4KB (QD=1) : 0.369 MB/s [ 90.0 IOPS]
Random Write 4KB (QD=1) : 0.639 MB/s [ 156.0 IOPS]
Random Read 4KB (QD=32) : 0.714 MB/s [ 174.3 IOPS]
Random Write 4KB (QD=32) : 0.651 MB/s [ 158.9 IOPS]
Test : 500 MB [E: 93.7% (321.4/343.1 GB)] (x5) Date : 2013/05/20 0:26:04 OS : Windows 7 Professional SP1 [6.1 Build 7601] (x64)
CrystalDiskMark 3.0.2 x64
2 USBs for Power
Sequential Read : 84.155 MB/s
Sequential Write : 79.341 MB/s
Random Read 512KB : 30.546 MB/s
Random Write 512KB : 28.847 MB/s
Random Read 4KB (QD=1) : 0.238 MB/s [ 58.0 IOPS]
Random Write 4KB (QD=1) : 0.592 MB/s [ 144.6 IOPS]
Random Read 4KB (QD=32) : 0.672 MB/s [ 164.0 IOPS]
Random Write 4KB (QD=32) : 0.635 MB/s [ 155.0 IOPS]
Test : 500 MB [E: 93.7% (321.4/343.1 GB)] (x5) Date : 2013/05/20 0:34:06 OS : Windows 7 Professional SP1 [6.1 Build 7601] (x64)
The disadvantages is the performance issues you experiened. – Ramhound – 2013-04-30T14:58:52.030
Does the external drive have two USB inputs? What does the manual recommend? – Brad Patton – 2013-04-30T15:04:23.677
Here's the answer you're looking for: http://superuser.com/a/193969/218300
– M.Bennett – 2013-04-30T15:37:57.197sorry, i meant i have not noticed any performance degradation. I will try and benchmark myself to see. – ericosg – 2013-04-30T16:45:11.787
@BradPatton it does not clarify what-so-ever. – ericosg – 2013-04-30T16:52:02.267
@Ramhound any idea to what degree? – ericosg – 2013-04-30T16:52:23.067
@ericosg contact the manufacture and ask – Ramhound – 2013-05-01T00:55:17.737
@Ramhound but generally, does anyone know if disks run at lower performance when provided with less power? – ericosg – 2013-05-01T09:33:58.820
1@ericosg - It really depends on the exact drive being used inside the enclosure. A general statement would be incorrect in many cases. A green drive for instance already requires less power, a higher speed 10,000 RPM drive will require more power, the power across USB 2.0 is different then USB 3.0. – Ramhound – 2013-05-01T11:03:37.653