I have no such a problem with my disk, so I think it's not normal.
You can use the 'smartmontools' utilities to check your disk (install it with the package manager).
Use this command to see all the info about your HD:
sudo smartctl -a /dev/sda
You can also perform some tests on the disk with these commands:
sudo smartctl -t short /dev/sda
sudo smartctl -t long /dev/sda
The first one performs a short test (a couple of minutes to complete it), the second one a long test (up to an hour to complete it).
If your HD is ok, then probably it's a power saving misconfiguration. Take a look at this thread
for more info.
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