Unwanted disc keeps spinning

6 Apr 2019 13:49:32

Rick Churchill

I have been playing around with cloning discs recently (the hard disc out of a Panasonic video recorder) and have had to download Ubuntu, a Linux distro, in order to use their terminal commands, as no other cloning software will work with the Panasonic.

In swapping external discs between computers I noticed that on the Mac an external disc when unmounted (ejected) hesitates for moment then goes on spinning and then has to be disconnected while still powered. Using Linux or Windows when unmounted (ejected) it is disconnected from the power and stops spinning.

Why is the Mac so reluctant to give up on an unwanted drive?

New information. After 6 and a half minutes the external drive stops (or sleeps)!

Re: Unwanted disc keeps spinning

7 Apr 2019 12:11:26

Euan Williams

In a word, indexing.

Re: Unwanted disc keeps spinning

7 Apr 2019 16:56:01

Rick Churchill

Thanks Euan.

So if the Mac is still reading the disc, although removed from the desktop (not shown in the desktop folder) and not writing to it, does that mean it is safe to unplug?

I have looked up preventing indexing on external drives but it looks like you have to connect the drive then tell Spotlight to exclude it which means there is no universal way of preventing any external drive from being excluded.

In most cases I would connect a 1TByte drive i.e. one that required 10 minutes of indexing time, to transfer only large files and so indexing, a useful function anyway, would have long ceased.

Re: Unwanted disc keeps spinning

7 Apr 2019 21:42:46

Euan Williams

If the external disc has removed itself (i.e. not removed by human hand) from the desktop, indexing should have ceased, and it should be safe to disconnect it, although in practice a short pause is recommended. Ten minutes seems wildly excessive and might be due to the terminal command setup. It's unlikely that the Panasonic drive is formatted to either the older macOS HFS+ or the current APFS, and a Linux or Windows format is possible.

Did you clone the Panasonic Drive to a Ubuntu Linux partition on your Mac -- or what? As you know, Linux and macOS are both fully certified UNIX operating systems. It may be that you got access to the data on the P-drive and simply copied that, rather than making a full clone.

There is too little information to make any further suggestion, although, having a Panasonic HD recorder I am interested!

Re: Unwanted disc keeps spinning

9 Apr 2019 14:51:33

Rick Churchill

The “disc-spinning-time-after-unmount/reject experiment” was done when I was making a universally acceptable formatted drive which could be used on Mac, Windows and Linux OS’s. I was moving the physical drive between computers (although both Linux and Windows are on the same computer). As you believe that indexing ceases when the icon is removed from the desktop it is strange that the disc continues to spin after indexing has taken place. There is conflicting advice on the internet as to whether drives should be removed whilst still spinning.

Although this is getting a bit outside of this forum just to clarify my cloning remarks: I cloned the Panasonic disc to a newly purchased disc using Linux terminal command dd (sometimes called data destruction) on my PC. I know nothing of Linux and have had a very steep learning curve to get to the point where I was confident that I was not about to clone the PCs own drive and destroy the computers OS! I am reasonably certain that the cloning was successful but am not confident enough to install the new drive and prove it until the old drive deteriorates further because there are risks associated with introducing a new drive without having the Panasonic installation disc.