Re: incremental rdiff-backup takes long

[Jonas Schöpf]

Hi!

Thank you again for your help!

With the "--no-fsync" argument, the backup succeeded after 13 minutes.

Cheers,
Jonas

On 6/1/21 9:53 PM, Jonas Schöpf wrote:
> Hi Patrik!
> 
> On 6/1/21 4:48 PM, Patrik Dufresne wrote:
>> Hello Jonas,
>>
>> Welcome to rdiff-backup ! Let me try to help you a bit more with you
>> problem.
> Thanks :)
>>
>> First, the first backup always take alot of time because rdiff-backup is
>> not like a simple copy and alot of overhead are done in the background
>> to put in place the first version of the data.
>>
>> Second, with your use case of 400GB, I would not expect a very long
>> elapsed time for subsequent backup. I have a couple of backups with
>> similar size and it roughly takes ~10-20 minutes over the Internet with
>> 400Mbps. But you might not have the same setup as I do.
>>
>> If $HOME and $DRIVE are both local, It's quite simple to narrow the problem.
>>
>> While running the backup with you command line, you might want to check
>> how the IO of your computer behaves. In the command line, try executring
>> `iostat -x -m 3` and take a look at the '%util' column. It displays the
>> percentage utilisation of the disk. If the value is near 90%, you have
>> found the culprit. The IO is your bottleneck.
>>
>> To help the situation, you might want to run the backup without fsync.
>> When Fsync is enabled, it forces the system to wait until the data is
>> written to the disk and persisted. For slow drives on USB, it may have a
>> huge impact on the performance. So try running rdiff-backup with
>> `--no-fsync`.
> 
> Thank you for your help.
> Sounds like this is the problem!
> 
> I will try your this tomorrow and report back if it works :)
> 
> Thank you all for your help!
> 
> Cheers,
> Jonas
> 
> 

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