Re: [gentoo-user] [OT] external conceptronic box

[Richard Fish]

Jorge Almeida wrote:

>On Wed, 26 Oct 2005, Richard Fish wrote:
>
>
>>One thing: you must be very careful of the power supply and requirements of
>>the HD.  I have several models of external chassis that provide 12V 1.7A of
>>power, and this is insufficient for modern (and _large_) disks, and will
>>result in disk read and write errors.
>>So I highly recommend a chassis that uses a power supply that provides
>>separate 12V and 5V inputs.  Judging from the pictures of the CHD3U I found,
>>it seems to support this, so it should be a good choice.
>>
>>
>>
>You mean 12V and 5A, right?
>
>

Nope.  I mean separate 12V and 5V inputs.  The case I use now comes from 
bytecc, although the same case sells under several different brands.

http://www.newegg.com/Product/Product.asp?Item=N82E16817145345

The power brick lists 5V/1.5A and 12V/1.8A, and has a 4-pin connector to 
the case.  Since 3.5inch hard disks require 12V and 5V inputs, this is 
really the ideal situation, as otherwise the case has to implement some 
kind of voltage transformer internally, which will itself lose power and 
you don't know how much current is then available for the 12V vs 5V 
inputs to the drive. 

 From what I could tell from the pictures of the Conceptronic, it also 
has a 4-pin power connector, so it should be fine.

>I've been to the shop and the case doesn't supply any info about
>delivered power. It does say it supports hds up to 400GB, though. (I'm
>planning to buy a 250GB Samsung, which seems to have a good
>capacity/price ratio.)
>

That's a good sign, since AFAIK all drives larger than 250G have 3 
platters, (vs 2 platters for the typical 250G drive) and thus consume 
more power.  So if they have tested with 400G drives, it should work 
fine with a 250.

Oh, final comment, don't be surprised by the relatively lackluster 
performance of the USB2 cases.  My 250G USB2 disks max out at around 
29MB/sec throughput.  When connected to an internal IDE bus, the disks 
run at >60MB/sec, and the USB2 bus doesn't max out until around 40MB/sec 
on my system.  But every USB2 drive I have ever plugged in to any system 
has been limited to 20-30MB/sec of throughput.

Of course, for backup purposes 29MB/sec is damn fast!

-Richard

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