Performance of SATA on USB port

vbimport

#1

I have the oportunity to buy an SATA external 320GB ‘Medion’ harddrive with 8mb cache and a reported 1200Mbits transfer rate, for 100 Euros. Seems like a very nice price but in reading some of the threads here, using a USB harddrive can have some problems.
I have two USB ports, one with a highspeed hub attached which supports my DSL connection, mouse and USB stick, the other is left free for connecting my Phillips DVR1660 drive mounted externally. I have always had trouble with the burn rate with this drive never reaching a speed of more than 2x.
Question: given that I have this problem with the burner, would I then have problems with connecting this harddrive to my Toshiba laptop? The USB port is verified as a 2.0 highspeed but I have yet to figure out what, if any, is the reason for the slow burn rate and now worry that I will not get full use from the new drive I would like to buy.
Any discusion on this to educate me would help my decision.
I really need the new space but just do not know what kind of drive to get. :confused:


#2

Any hard drive will be limited to about 20MB/sec write speed and maybe 25MB/sec read speed on USB2, assuming the USB is working well.

Sounds like your USB is not working well. Also keep in mind that the more stuff you have running through the USB, the slower it gets.


#3

Is each USB port independent or are are their bandwidths tied together in some way.
I have one that is not used for anything else but an individual device but the other is, as I said, used to connect to my DSL router and the use of my mouse.

Is there any way of increasing this speed or checking it out for proper function? I see nothing more in my Device Manager then it has no conflicts and is working properly.


#4

The 2 USB ports are on the same chip on the mainboard, so they share resources. Have you tried burning with the modem & mouse disconnected? Less than 2X DVD burn speed sounds suspiciously like USB 1.1 (not 2.0). It should do more. Have you done a “Burst Rate” test in Nero CD DVD Speed?

The external SATA hard disk probably has USB and eSATA interfaces, so if you’re not happy with USB speed, you can also use an eSATA PCMCIA-card (extra expense).

And if your laptop has these ports, perhaps you can consider using an ethernet modem and a PS/2 mouse to free up USB (but that would defeat the purpose of the cheap hard disk price as well).


#5

As stated, all USB devices will be sharing the resources of the single USB controller. Add to that the fact that the USB controller shares resources with everything that’s on the PCI bus, including hard drive, sound, PCMCIA cards, and just about everything else.

Use CDSpeed to run a transfer rate test on the external burner. That’ll tell you what the speeds reached during reading are. Also run a burn test with a blank disk in the burner, that’ll tell you what the max write speeds are.


#6

I used Nero tools as suggested to test my external burner and if I can understand the chart, the speed of the drive begins at 21.28x and ends at 31.66x for an average of 31.16x, using a CD. Are these the read and write speeds you speak of CDan? If so, my USB port seems to be handling transfer rates OK.
The burst rate for the DVD was 7MB/s. How does this compare with other burst rates?
I have not tried these test with the other devices on the USB port removed, which I shall do and make comparisons.


#7

Use a DVD for the transfer rate test. (you don’t need to run all the tests, just the one) CD data rates are much lower. You can also save the graph as an image file and attach it to your post here. (icon for saving is in the upper right in CDSpeed)

Write speed would be tested with a blank disc, and wastes the disc.


#8

The 7 MB/s burst rate is very low for USB 2.0 but has been known to happen. Either the USB implementation of your laptop itself is poor or its compatibility with the external enclosure/drive is. This confirms the burn speed problem and doesn’t bode well for the USB hard drive speed (although if it’s a hardware compatibility issue, it may just as well work better than the burner). Ideally you’re looking for something like 23-24 MB/s burst rate to allow up to 16X speed DVD burning.


#9

Ah, you may have hit on something, Cressida. I remember, in my lurking here, that chipset within the enclosure would have something to do with the speed of the drive. My burner is an internal model which I then cannibalized into an external harddrive case I had. (it is a 3.5" case so the burning sits on top of the case) the chipset is Cypress CY7C68300A which is supposed to be able to operate at a full 12mbps however, perhaps the drive and this box are not working that well together?
CDan, I did try to post a screen shot of my graph results but in using the ‘insert image’ all I got was the html code (

(if an image doesn’t appear here then this was another failed attempt to use the ‘insert’ feature. UGH! :stuck_out_tongue: )


#10

Hey Barbigee

If you want to [B]add a picture[/B] you have on your hard-drive, write your text here like this, then click below as shown

[B]here[/B] to manage attachments


#11

External enclosures can slow things up. I don’t know the Cypress chip you have. I have two that I know as Cypress AT2 and Cypress AT2+. The AT2 gives me a burst rate of 7 MB/s. The AT2+ gives a burst rate of 23 MB/s.


#12

I use an old Iomega 5.25" enclosure with the same Cypress CY7C68300A chip, [B]BarbiGee[/B], and it is good for 16X burns with my LiteOn/Sony burners. BenQ/Philips drives are a bit more difficult to use externaly though (I believe, cause I have little or no experience with them).

12mbps is the theoretical max. transfer speed for USB 1.1. For USB 2.0 this is 480mbps (= 60MB/s).


#13

oh THAT’S how you do it. The benefits of scrolling all the way down to see final instructions. :clap:

NOW! Here is the screen shot of my DVD test.

[B]NeroDVDtest[/B]






#14

A common error. This is a burst rate speed only. Since USB2 is a “one-way” connection, actual speeds will likely be well below 30MB/sec, and 20 would be considered average on sustained transfers. Many USB controllers will struggle to reach 15.


#15

Definitely a problem there. Try setting the max burn speed to 12x in CDSpeed. (hope you don’t mind wasting a few discs)


#16

CDan, I don’t mind wasting a few discs but should they be DVDs or CDs for testing (I would assume DVDs since that is the problem area.)

However, I just installed the new SATA harddrive an hour ago and ran a DiskBench test on the drive. This test was run with the drive attached to the USB highspeed hub, NOT to the unused port I generally use for the burner. I think it did quite well. (I will run another test using the other port and compare)

Based on this test I can only assume that the chipset of the enclosure I am using for the burner is the culprit for slow transfer rates.

Here is the test results on the new harddrive.



#17

I removed all USB devices except keyboard and the external DVD burner (LG E10L) itself, and the Burst rate improved from ~ 14Mb/s to 24Mbs.


#18

It would appear that a new USB architecture is needed to handle these bandwidth -intensive devices we are using. I have not read anything nor seen any tech reports that this is going to take place. :frowning:


#19

Perhaps Firewire (especially 800) might be a better option?

I can run OS X on my MacBook via Firewire 400 external 320Gb Hard Drive without any problems so far.


#20

No question that firewire is better than USB, it provides a much higher throughput (bandwidth) due to being a 2-way connect. Differences on the order of 30% are not unusual. But it’ll still be on the PCI bus, so limitations may exist on an overloaded system.