On 18.05.2021 06:33, hongy...@gmail.com wrote:
> On Ubuntu 20.04, each time when I start the machine and enter the
> system, I find that the hard disk indicator light will be flashing
> for a very long time. As a result, during this period, the data IO
> performance is very poor.

In the 1970's a school teacher who had been involved with computers
in the 1960's or earlier told us about a flashing light indicating
a problem in their computer system. The system seemed to work fine,
but they decided to call the technical support. The engineer opened
the system, did his work, wrote his invoice, and left the place.
Curiously the folks opened the system to see what the engineer has
done. He had just disconnected the flashing light. (And the system
continued running without fault; as it always did.)

>
> Any hints for debugging/fixing this problem?

And what is "this" problem?

Obviously the system seems to be doing some (most likely intended
and configured) task. What could that be? A disk backup or other in
cron defined jobs? A consistency check? The building of the locate
database? Who knows. How can we know?

If you doubt that your system is doing something useful on the disk
then inspect the cron-files and possibly the system log files as a
hint what to disable, or to get the keywords for a google search or
another post with more relevant information beyond a flashing light.

Janis

>
> Regards, HY
>

On 18.05.2021 at 12:07, Janis Papanagnou scribbled:

> On 18.05.2021 06:33, hongy...@gmail.com wrote:
>
> > On Ubuntu 20.04, each time when I start the machine and enter the
> > system, I find that the hard disk indicator light will be flashing
> > for a very long time. As a result, during this period, the data IO
> > performance is very poor.
>
> [...]
>
> > Any hints for debugging/fixing this problem?
>
> And what is "this" problem?
>
> Obviously the system seems to be doing some (most likely intended
> and configured) task. What could that be? A disk backup or other in
> cron defined jobs? A consistency check? The building of the locate
> database? Who knows. How can we know?

UNIX systems aren't intended to be switched off and on all the time, as
is the case with MS-Windows and macOS. UNIX does things in the
background — system maintenance, making backups, et al — all the time,
and the heaviest tasks are usually scheduled for somewhere between
midnight and 04:00. If the machine is switched off during that time,
then all of those tasks will be run on the next boot.

Also, that's not a topic to do with the shell, and therefore, off-topic
here. A better place to ask would be alt.os.linux.debian or
comp.os.linux.hardware.

But then again, we're dealing with Hongyi, the most demanding and
worst-paying employer in the world.

<roll eyes>
--
With respect,
= Aragorn

On 18.05.2021 13:02, Aragorn wrote:
>
> UNIX systems aren't intended to be switched off and on all the time, as
> is the case with MS-Windows and macOS. UNIX does things in the
> background — system maintenance, making backups, et al — all the time,
> and the heaviest tasks are usually scheduled for somewhere between
> midnight and 04:00. If the machine is switched off during that time,
> then all of those tasks will be run on the next boot.

This may have (slightly) changed since Linux is getting spread across
more and more client systems. A shutdown of a Linux client is nothing
that looks too strange, especially not if run on a laptop where also
suspending the system is common. In case of waking up a suspended
system I'd expect missed cron task-dates to also run close to the
wakeup-time.

Janis

On 2021-05-18, Aragorn <thorongil@telenet.be> wrote:
> UNIX systems aren't intended to be switched off and on all the time, as
> is the case with MS-Windows and macOS. UNIX does things in the
> background — system maintenance, making backups, et al — all the time,

Unix-based MacOS went beta in 2000. Windows has lots of services
running which do things in the background.