rsync + tar archive performance

[Leen Besselink]

On Fri, Feb 24, 2012 at 03:16:16PM +0100, Bartlomiej Radziszewski wrote:
> On 02/24/12 14:46, Leen Besselink wrote:
>> On Fri, Feb 24, 2012 at 01:45:13PM +0100, Bartlomiej Radziszewski wrote:
>>> Hi,
>>>
>> Hi,
>>
>>> I have issue with taring speed on the directory created over rsync.
>>>
>>> I'm putting directory on a system using rsync (rsync -rv) then tarred it
>>> then puting the same directory on the server again using cp (cp -r) and
>>> tarred it.
>>> There is a result of my test http://pastebin.com/JsrVZps0 - looks like
>>> tar working two times slower on directory copied by rsync.
>>>
>>> - m4cp and m4sync contain same files/dirs (from ~100KB to ~3MB)
>>> - using rsync 3.0.7-2 (debian squeeze)
>>> - fs - ext4
>>>
>>> I'm not sure what's wrong there.. waiting for your suggestions.
>>>
>> Could it be there is nothing wrong ?
>>
>> I assume the files already existed in the directory when rsync did it's
>> work. Because I think rsync was probably doing a 'quick check', where it looks
>> at the files properties like filesize and last modification time. From the manual:
>>
>>         -I, --ignore-times
>>                Normally rsync will skip any files that are already the same size and have the same modification timestamp.  This  option  turns  off  this
>>                “quick check” behavior, causing all files to be updated.
>>
>>         --size-only
>>                This  modifies  rsync’s “quick check” algorithm for finding files that need to be transferred, changing it from the default of transferring
>>                files with either a changed size or a changed last-modified time to just looking for files that have changed in size.  This is useful  when
>>                starting to use rsync after using another mirroring system which may not preserve timestamps exactly.
>>
>> So the files weren't read from disk by rsync after you cleared the cache, so they had to be read from disk instead of the filesystem cache when tar was running.
>>
> Hi Leen,
>
> Thanks for your replay. I'm not sure if you correctly understand my problem.
>

I didn't understand it correctly, luckily I have an excuse I'm sick at home. ;-)

> I have two dirs 'm4cp' (created by cp -r) and 'm4rsync' (created by  
> rsync -rv) and next i'm running tar on these dirs..
> And looks like tar processing on rsynced directory is two times slower  
> then on the directory created by cp.
>
> Hope right now is more clear..
>

But is the data the same ? Because the filesizes are smaller for the second.

Or are these something like filesystem-image files ? Maybe you stored them
as sparse files ?

Could that be the reason for the difference in speed ?

> Regards,
> Bartek
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