Re: [gentoo-user] Copying data efficiently

[Mick]

On Saturday 17 May 2014 04:33:57 meino.cramer@×××.de wrote:
> Hi,
>
> is there any tool in the Gentoo portage which may speed up (make it
> mopre efficient) the following task:
>
> On my HD there are data I want to copy to two identical external HDs.
> These HDs are of the same type/model and each is separately
> connectable via USB to my PC (...these two of the typical mobile external
> USB-HDs).
>
> Instead of copying the data twice from my PC to eah of the HDs I want
> to do it once...like I would be able to give the cp-command two
> instead of one target where to copy two.
>
> The result should be two identically populated external HDs, each of
> them useable/readable without the need to the other one.
>
> What tool of the portage tree I able to accomplish this task?
>
> Best regards,
> mcc


1. You could set up the two ext drives as a mirrored RAID and use your 
copying/tar-ing/dd tool of choice.


2. Or you could use pipe and tee to split the feed into any devices you want, 
e.g.:

  pv /dev/sda1 | tee >(dd of=/dev/sdb1) >(dd of=/dev/sdc1) 


3. Or you could use a sequential copy:

  cp -a /home /dev/sdb1/ && cp -a /home /dev/sdc1


NOTES: 

a) Unlike other commands, pv will give you a progress bar so that you know how 
long your back up is taking.

b) The 3rd example above will copy sequentially, but depending on the size of 
the file(s) the second copy may be read from cache.

c) If you're doing this over the network then you can use nc in listening mode 
at the receiving end, or ssh if the network is untrusted.


I'm interested to see what other ways will be suggested for this task.

-- 
Regards,
Mick