GNU bug report logs - #22277
'dd' - stats are not what expected

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Message #19 received at 22277 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Mike Fiedler <micfied <at> yandex.com>, 22277 <at> debbugs.gnu.org
Subject: Re: bug#22277: 'dd' - stats are not what expected
Date: Thu, 31 Dec 2015 21:51:19 +0000

[Message part 1 (text/plain, inline)]

On 31/12/15 10:18, Pádraig Brady wrote:
> unarchive 17505
> forcemerge 17505 22277
> stop
> 
> On 31/12/15 01:11, Mike Fiedler wrote:
>>  
>> Hi,
>>  
>> I ran one of my favorite utilities 'dd' again this evening, this time with bs=1G ( IEC ) - I usually do 1M but this time I dealt with more data to be copied...
>> I had to copy about 215 GiB of data from one to another drive ( offset 215 GiB was about the end of the last partition ).
>> So I did:
>>  
>> $  dd if=/dev/sdb of=/dev/sda bs=*1G* count=*222*
>> 222+0 records in
>> 222+0 records out
>> 238370684928 bytes (*238 GB*) copied, 1275.03 s, 187 MB/s
>>
>> When it finished, I got a bit confused, and I asked myself a question if the data I requested did really get copied..  of course it did, but I was not expecting 238 GB to be shown.
>> To make sure I calculated the 512 byte sector end number out of the 238370684928 bytes 'dd' result and compared it with the output of fdisk showing the last sector of the last partition... I was fine.
>>  
>> I think, and many others have a same opinion, 1kB = 1000B, etc, should be banned from use in the IT world, and banned from use by the sales people.
>>  
>> The point is, as you probably noticed, if dd is told to use IEC, let's stick to IEC and not get the results in whatever artificial decimal crap....
>> It can not only confuse, but utility like 'dd' should be 100% specific about handling the units, and there should be not a bit of doubt when it spits out the results.
>> If I would use 1K in this case, I would not notice the difference - my brain is simply too simple, and small, but 1G should at least result in displaying 222 GiB and for sure not GB.
> 
> I have to agree, and this has come up a few times now.
> 
> The number in brackets is not exact and informational for human consumption,
> so we should make an effort to be less confusing.
> There was a proposed patch at:
> http://debbugs.gnu.org/cgi/bugreport.cgi?bug=17505#37
> which auto determines the appropriate base from the amount output,
> to output the number with the least amount of info loss.
> 
> There were some issues noted with that,
> but IMHO they were lesser than the current issue.
> 
> We will have to be careful to not corrupt output
> when switching with status=progress (due to possibly shorter status line).

Resending as previous email seems dropped somewhere:

The attached auto sets the units.
For status=progress this is done based on output block size,
for the final transfer stats, it's done based on the transferred byte count.

cheers,
Pádraig

[dd-stats-units.patch (text/x-patch, attachment)]

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