[Novalug] need dd help
John Franklin
franklin@elfie.org
Mon Feb 13 08:58:20 EST 2012
Can you open another shell and run vmstat? How fast is it writing?
jf
On Feb 13, 2012, at 5:49 AM, Jay Hart wrote:
> After 8 hours, I'm still waiting for the dd command to complete.
>
> Jay
>
>> Sounds a bit short. 100MB/s write speed would take 10,000 seconds to zero a
>> 1TB drive.
>>
>> jf
>>
>> On Feb 13, 2012, at 12:36 AM, Jay Hart wrote:
>>
>>> Not sure I understand what you are saying. I should take a value such as 8
>>> seconds and multiply by a 1000?
>>>
>>> So 8000 seconds should be over 2 hours and 10 minutes. Sound about right to
>>> zero a 1TB drive?
>>>
>>> Jay
>>>
>>>> On Sun, Feb 12, 2012 at 10:37:22PM -0500, Jay Hart wrote:
>>>>> Jon,
>>>>>
>>>>> So this will wipe my entire drive, 1k at a time. 1TB will take a while, I
>>>>> suspect.
>>>>
>>>> Preview it by doing
>>>>
>>>> time dd if=/dev/zero of=junk bs=1k count=1048576
>>>>
>>>> and multiple the time by 1000. That should give an outer limit.
>>>>
>>>> You could also try
>>>>
>>>> time dd if=/dev/zero of=junk bs=4k count=262144
>>>>
>>>> and see if there is a speed-up.
>>>>
>>>> Running the 1k command on three different systems I got 29,
>>>> 11, and 3 seconds. Guess which one had the Solid State Drive :)
>>>> The 4k command ran about 20% faster.
>>>>
>>>> Jon
>>>>>
>>>>>> On Sun, Feb 12, 2012 at 10:17:04PM -0500, Jay Hart wrote:
>>>>>>> I think this command with totally wipe a drive:
>>>>>>>
>>>>>>> dd if=/dev/zero of=/dev/devicename bs=1k
>>>>>>>
>>>>>>> Yes/no. what exactly does the "bs=1k" do???
>>>>>>
>>>>>> By default dd uses input and output buffers of 512 bytes.
>>>>>> These can be changed individually with ibs= and obs=.
>>>>>> Your option bs= changes both buffer sizes to 1024 bytes.
>>>>>>
>>>>>> I find when making large transfers like this that a
>>>>>> larger buffer size greatly speeds up dd. I'd suggest 4k.
>>>>>>
>>>>>> jl
>>>>>> --
>>>>>> Jon H. LaBadie novalugml@jgcomp.com
>>>>>> 11226 South Shore Rd (703) 787-0688 (H)
>>>>>> Reston, VA 20190 (609) 477-8330 (C)
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>>>>>
>>>>>
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>>>>
>>>> --
>>>> Jon H. LaBadie novalugml@jgcomp.com
>>>> 11226 South Shore Rd (703) 787-0688 (H)
>>>> Reston, VA 20190 (609) 477-8330 (C)
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>>>
>>>
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>>
>> --
>> John Franklin
>> franklin@elfie.org
>> ICBM: 39º 01' 58.4"N 77º 24' 49.6"W Z+84m
>>
>>
>
--
John Franklin
franklin@elfie.org
ICBM: 39º 01' 58.4"N 77º 24' 49.6"W Z+84m
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