What is the real-world speed (stream, latency) of USB3 and USB2 over SATA?
It is easy to find streaming speed comparisons, but more difficult to find latency comparisons in the same setup.
Answer to follow in a momemt.
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On an ASUS Z87 motherboard with an intel i7-4770K with gobs of memory and ubuntu 14.10, the rough performance comparison of a first-gen Intel 80gb SSD drive (X25-M), using the ioping utility on an ext4 filesystem, the following is a rough estimate of read-performance:
SPEC: 250MB/sec,
SATA: 240MB/sec, 1000 iops, 1ms latency
USB3: 190MB/sec, 750 iops, 1.3ms latency
USB2: 43MB/sec, 200 iops, 6ms latency
Of course, this will be different for different setups. The point of this table was to add some latency and iops stats in a non-theoretical comparison. The rest below are merely details on the above.
More Details follow
All Tests Run On An Intel 80GB First-Gen Drive, X25-M.
Direct-Access ATA INTEL SSDSA2M080 02HA PQ: 0 ANSI: 5
Intel Posted X25-M Drive Specs:
Read: 250MB/s
Write: 70MB/s
Latency Read: 65us
Latency Write 85us
IOPS: read=35k. write=300 to 6600
Motherboard: Asus Z87 Gryphon w/ USB 3.0 port.
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on the SATA bus:
# ioping -RL .
--- . (ext4 /dev/sdb1) ioping statistics ---
2.8 k requests completed in 3.0 s, 952 iops, 238.0 MiB/s
min/avg/max/mdev = 999 us / 1.1 ms / 2.1 ms / (85 us)
# ioping -RL .
--- . (ext4 /dev/sdb1) ioping statistics ---
2.8 k requests completed in 3.0 s, 956 iops, 239.2 MiB/s
min/avg/max/mdev = 1.0 ms / 1.0 ms / 7.6 ms / (149 us)
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on the USB 3.0 superspeed bus:
Bus 003 Device 011: ID 152d:2509 JMicron Technology Corp. / JMicron USA Technology Corp. JMS539 SuperSpeed SATA II 3.0G Bridge
# ioping -R .
--- . (ext4 /dev/sdd1) ioping statistics ---
11.3 k requests completed in 3.0 s, 3.8 k iops, 14.8 MiB/s
min/avg/max/mdev = 247 us / 264 us / 4.6 ms / (49 us)
# ioping .
4.0 KiB from . (ext4 /dev/sdd1): request=1 time=1.6 ms
4.0 KiB from . (ext4 /dev/sdd1): request=2 time=333 us
... ^C
--- . (ext4 /dev/sdd1) ioping statistics ---
12 requests completed in 11.5 s, 2.3 k iops, 9.1 MiB/s
min/avg/max/mdev = 290 us / 427 us / 1.6 ms / (344 us)
# ioping -RL .
--- . (ext4 /dev/sdd1) ioping statistics ---
2.2 k requests completed in 3.0 s, 748 iops, 187.0 MiB/s
min/avg/max/mdev = 1.3 ms / 1.3 ms / 3.6 ms / (96 us)
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on the USB 2.0 high-speed bus:
# ioping -R .
--- . (ext4 /dev/sdd1) ioping statistics ---
509 requests completed in 3.0 s, 170 iops, 42.6 MiB/s
min/avg/max/mdev = 5.8 ms / 5.9 ms / 6.3 ms / (67 us)
# ioping -RL .
--- . (ext4 /dev/sdd1) ioping statistics ---
510 requests completed in 3.0 s, 170 iops, 42.7 MiB/s
min/avg/max/mdev = 5.8 ms / 5.9 ms / 6.3 ms / (42 us)
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USB3 Bridge Device
Bus 003 Device 011: ID 152d:2509 JMicron Technology Corp. / JMicron USA Technology Corp. JMS539 SuperSpeed SATA II 3.0G Bridge
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x152d JMicron Technology Corp. / JMicron USA Technology Corp.
idProduct 0x2509 JMS539 SuperSpeed SATA II 3.0G Bridge
bcdDevice 1.00
iManufacturer 1 JMicron
iProduct 11 Usb production
iSerial 3 00A123456A8D
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 32
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 4 USB Mass Storage
bmAttributes 0xc0
Self Powered
MaxPower 2mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk-Only
iInterface 6 MSC Bulk-Only Transfer
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Binary Object Store Descriptor:
bLength 5
bDescriptorType 15
wTotalLength 42
bNumDeviceCaps 3
USB 2.0 Extension Device Capability:
bLength 7
bDescriptorType 16
bDevCapabilityType 2
bmAttributes 0x00000002
Link Power Management (LPM) Supported
SuperSpeed USB Device Capability:
bLength 10
bDescriptorType 16
bDevCapabilityType 3
bmAttributes 0x00
wSpeedsSupported 0x000e
Device can operate at Full Speed (12Mbps)
Device can operate at High Speed (480Mbps)
Device can operate at SuperSpeed (5Gbps)
bFunctionalitySupport 1
Lowest fully-functional device speed is Full Speed (12Mbps)
bU1DevExitLat 10 micro seconds
bU2DevExitLat 32 micro seconds
Container ID Device Capability:
bLength 20
bDescriptorType 16
bDevCapabilityType 4
bReserved 0
ContainerID {00010203-0405-0607-0800-000000000000}
Device Status: 0x0001
Self Powered
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