Force the kernel to unregister a drive and then initialize it again

ThomasHunter

2/11/23, 12:21 AM

I had a drive that would seem to be mounted and busy no matter what I did. But since I didn't want to reboot the whole system, I ran echo 1 > /sys/block/sd*/device/delete to force the kernel to "unplug" or unregister the drive.

Then I unplugged and replugged the SATA power cable of the disk, it showed up again in the system and worked as expected.

But what could I've done if I didn't have physically access to it? What would be the alternative to physically unplugging the SATA cable so the system could see it again after running echo 1 > /sys/block/sd*/device/delete ?

102

0 + 0

ubuntu

hard-drive

mount

Score:2

Server

BitGen01100000

2/11/23, 10:30 AM

You could rescan the SCSI host bus by running the following command

echo "- - -" > /sys/class/scsi_host/host0/scan

NOTE: The host0 part of the command above is the host ID. And you might have multiple/other host ID's on your machine. Which means that if the command above doesn't get you the drive back, you might have to change the host ID to match what you have on your machine.

You can look up which host ID's you have available on your machine by running

ls /sys/class/scsi_host

Which on my machine returns

host0  host1  host2  host3  host4  host5

So look up your host ID's and run the first command on each ID to make sure that the drive gets detected.

Edit:

To repeat this command for each host ID you could just put in into a loop like this:

for host in /sys/class/scsi_host/host*/scan; do echo "- - -" > $host; done

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ThomasHunter

2/14/23, 1:55 AM

Thank you. I seem to have 73 host devices on that one machine. Is there a way how to simply scan them all without specifying just one? Or maybe do some loop script?

BitGen01100000

2/14/23, 2:37 PM

@ThomasHunter That's a lot of host ID:s! I have added some code to my answer that allows you to run the command for each host ID. Note however that it can take a few seconds, maybe up to a few minutes (depending on your hardware) when scanning that many hosts in a row! BTW If my answer solved your problem I would appreciate if you marked my answer as the accepted answer! :)

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Force the kernel to unregister a drive and then initialize it again

TH: บังคับให้เคอร์เนลยกเลิกการลงทะเบียนไดรฟ์แล้วเริ่มต้นใหม่อีกครั้ง

RO: Forțați nucleul să anuleze înregistrarea unei unități și apoi să o inițializați din nou

RU: Заставить ядро отменить регистрацию диска, а затем снова его инициализировать.

VI: Buộc hạt nhân hủy đăng ký ổ đĩa rồi khởi tạo lại

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