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On Mon, May 14, 2012 at 10:52 AM, walt <w41ter@×××××.com> wrote: |
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> On 05/13/2012 02:00 PM, Michael Mol wrote: |
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>> On Sun, May 13, 2012 at 4:28 PM, walt <w41ter@×××××.com> wrote: |
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>>> > I have a usb3 docking station which is showing some behavior I don't |
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>>> > understand: |
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>>> > |
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>>> > #hdparm -t /dev/sdc |
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>>> > |
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>>> > /dev/sdc: |
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>>> > Timing buffered disk reads: 266 MB in 3.01 seconds = 88.43 MB/sec |
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>>> > Timing buffered disk reads: 266 MB in 3.02 seconds = 88.10 MB/sec |
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>>> > Timing buffered disk reads: 306 MB in 3.01 seconds = 101.72 MB/sec |
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>>> > Timing buffered disk reads: 266 MB in 3.00 seconds = 88.59 MB/sec |
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>>> > Timing buffered disk reads: 306 MB in 3.00 seconds = 101.84 MB/sec |
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>>> > Timing buffered disk reads: 306 MB in 3.00 seconds = 101.86 MB/sec |
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>>> > |
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>>> > That's all the same disk, repeating hdparm as fast as I could. The |
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>>> > disk was not even mounted at the time, and no other disks were active. |
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>>> > |
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>>> > Two very different but reproducible numbers, changing values at random |
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>>> > times. The only thing I can think of is that the disk may be doing |
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>>> > a SMART self-test, but for some reason the USB connection prevents |
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>>> > me from accessing the data so I can't test my theory. |
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>>> > |
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>>> > Any other ideas? |
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> |
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>> bonnie++? |
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> |
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> As Volker suggested, I'm not worried about this but I'm always up for |
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> learning new stuff, so I tried bonnie++ on the machine's main hard |
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> drive and on the outboard docking station (both Western Digital). |
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> |
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> Here is bonnie's printout for each drive. Can you tell which is which? |
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> (They must have hired a special consultant to design the format ;) |
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|
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Yeah, Bonnie++'s output format is a PITA in some environments. It's |
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just a table, but it's almost unreadable with variable-width type, and |
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it's worse when it wraps. I had to copy it into a text editor to be |
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able to read it. |
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|
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> |
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> Version 1.96 ------Sequential Output------ --Sequential Input- --Random- |
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> Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- |
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> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP |
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> a6 7G 403 97 77669 10 36911 7 2820 83 104831 11 225.0 4 |
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> Latency 38221us 1376ms 681ms 68894us 160ms 965ms |
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> Version 1.96 ------Sequential Create------ --------Random Create-------- |
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> a6 -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- |
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> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP |
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> 16 17246 25 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ |
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> Latency 2363us 563us 653us 157us 10us 238us |
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> 1.96,1.96,a6,1,1337025021,7G,,403,97,77669,10,36911,7,2820,83,104831,11,225.0,4,16,,,,,17246,25,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,38221us,1376ms,681ms,68894us,160ms,965ms,2363us,563us,653us,157us,10us,238us |
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> |
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> |
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> |
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> Version 1.96 ------Sequential Output------ --Sequential Input- --Random- |
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> Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- |
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> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP |
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> a6 7G 714 99 92174 11 24808 4 3938 96 112295 14 128.1 3 |
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> Latency 11493us 1582ms 233ms 25883us 22036us 5344ms |
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> Version 1.96 ------Sequential Create------ --------Random Create-------- |
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> a6 -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- |
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> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP |
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> 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ |
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> Latency 2515us 517us 2818us 1271us 18us 293us |
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> 1.96,1.96,a6,1,1337028303,7G,,714,99,92174,11,24808,4,3938,96,112295,14,128.1,3,16,,,,,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,11493us,1582ms,233ms,25883us,22036us,5344ms,2515us,517us,2818us,1271us,18us,293us |
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|
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I'd guess the second printout is the USB drive. It has a much higher |
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latency on the sequential input test. But that's the only big |
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difference I can spot. |
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And I'd disagree with Volker on the "It's USB..." assessment. USB3 is |
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a _very_ different animal from earlier versions. You get nice things |
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like DMA, and your CPU usage is far lower than USB2, since the CPU |
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doesn't have to poll the USB controller for status updates. Honestly, |
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I'm very impressed at how similar those two printouts look, stat wise. |
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It's a close call to be able to identify which is which, and I'm not |
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really confident I did. |
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|
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-- |
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:wq |
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