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Re: [OM] Western Digital My Passport Essential USB2.0-Powered External D

Subject: Re: [OM] Western Digital My Passport Essential USB2.0-Powered External Drives
From: "C.H.Ling" <ch_photo@xxxxxxxxxxxxx>
Date: Tue, 3 Feb 2009 13:36:37 +0800
My experience is if you have a large set of files to copy the result is 
quite accurate (did many tests in the pass twenty years), I bet no more than 
20% variation in most cases unless your dirve is almost full. To gain more 
speed you better go with a 10000rpm drive or a RAID setup.

C.H.Ling

----- Original Message ----- 
From: "Chuck Norcutt"

> Probably a fair test if the drives were otherwise fairly empty such that
> the source data was relatively sequentially organized on the drive.
> Otherwise, if the data was scattered on one drive and not the other,
> seek and rotational delays would be greater on the drive with the
> scattered data.
>
> Chuck Norcutt
>
> C.H.Ling wrote:
>> Sorry, overlooked the second part. I did the comparison by copying SATA 
>> to
>> USB and SATA to SATA with the same 20GB data. I have not tried to check 
>> the
>> Read rate only.
>>
>> C.H.Ling
>>
>> ----- Original Message ----- 
>> From: "C.H.Ling"
>>
>>> So when we are talking about external drives for backup, then writing 
>>> time
>>> is also very important, eSATA does not has that much advantage here.
>>>
>>> C.H.Ling
>>>
>>> ----- Original Message ----- 
>>> From: "Chuck Norcutt"
>>>
>>>> AS I said the other day, disks spend a lot of time just trying to get 
>>>> to
>>>> were they're going and, once they get there, waiting on the correct 
>>>> data
>>>> to rotate around to where the head is.  They all seek to where they're
>>>> going at very similar rates and, assuming the same RPM on the platters,
>>>> they all wait at the same speed.  Actual data throughput gets dragged
>>>> down by all the mechanical delays.
>>>>
>>>> But do be aware of what you're comparing.  If you are simply reading
>>>> from the USB drive into memory but reading and writing between the two
>>>> SATA drives then the write operation has the SATA drives at a big
>>>> disadvantage.  Writing takes longer than reading and the reading from
>>>> drive 1 can't go any faster then the writing to drive 2 once the cache
>>>> is full.
>>>>
>>>> Chuck Norcutt
>>>>
>>>>
>>>> C.H.Ling wrote:
>>>>> 5x! Did you ever made a real comparison? I got 22MB per second for USB
>>>>> and I
>>>>> can't get over 30MB with SATA to SATA (two hard disks inside the same
>>>>> PC). I
>>>>> believe the HD sustain rate and other overheads in the computer 
>>>>> limited
>>>>> the
>>>>> data rate a lot.
>>>>>
>>>>> C.H.Ling
>>>>>
>>>>> ----- Original Message ----- 
>>>>> From: "Moose"
>>>>>> I'm simply not buying any external HD which is USB 2.0 only. eSATA is
>>>>>> WAY faster, 5x the speed, and only a very few $ more, if that. Maybe 
>>>>>> it
>>>>>> shouldn't make a difference for a drive planned for backup use only,
>>>>>> but
>>>>>> it does for me. I simply find it easier when the process goes faster.
>>>>>>
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>>>>
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>>
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> 

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