information switch – What precisely impacts the studying of sparse picture information?

I’ve an 8T sparse picture file in Time Machine named information.img with precise information area of 24G.

sh-3.2# ls -lash information.img

24G -rw-r--r-- 1 eric employees 8.0T 6 28 21:49 information.img

As a result of its measurement far exceeds the scale of the onerous disk, it can’t be restored by Time Machine (I’m curious why it may be backed up however not restored) nor can or not it’s copied or moved. It requires particular instructions to function, and after checking some data, I realized that tar and cp are most likely usable.

After retesting, the cp –sparse=at all times SOURCE DEST is executed very quick and properly underneath the identical quantity, and the 24G information is accomplished instantly, but when it’s not in the identical quantity, cp –sparse=at all times will likely be executed on a regular basis, and the scale of the DEST file will exceed 24G till the disk area is occupied.

Then the possible command is tar cSf. With a view to monitor the progress, the pv parameter is added. The ultimate command format is as follows:

tar cSf - information.img | pv -s $(du -sk information.img | awk '{print $1}') | tar -C path/to/DEST -xSf -

However the execute outcomes are disappointing. Time is transferring however no information is learn.

After the pressure interrupt command,I examined it with an 8G file (a couple of Okay of precise information) and it took 16 seconds.

A easy calculation exhibits that an 8 TB file could take greater than forty hours.

Ding ding ding, after some guesswork and experimentation, I out of the blue found that the studying pace in root mode is regular.It took lower than two minutes to execute.

Query:

Why can I learn the file usually in root mode however very slowly in regular person mode? Is that this not associated to permissions?