How to detach a disk in Linux (simulate a crash of partition/disk)?

Question

For testing purpose I need to simulate a crash of the disk (by detaching it) while other processes are using it.
I tried:

umount -f /srv/node/d1/

It doesn't want to unmount it. It shows me the next message:

umount: /srv/node/d1: target is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

There several processes which I don't want to stop manually because it will not be a crash. Does somebody know how to just detach a disk in linux? It would be more easy to detach it physically but I am using a virtual machine with virtual disks.

may be echo "1" >/sys/dev/block/<id>/device/delete , where <id> is the id of a block device? — Serge, Oct 07 '16 at 14:04
You can simulate failures of disks using scsi_debug kernel module. Or do you need to test one of your existing real devices? — rudimeier, Oct 07 '16 at 14:10
If this is a virtuel machine you can "unpresent" the disk. (not sure that will properly simulate a crash) — Archemar, Oct 07 '16 at 14:41
It depend on virtualization system, in vmware properties -> disk -> remove — Archemar, Oct 08 '16 at 08:33
I am using VirtualBox... It doesn't allow any changes when a VM is running. — Oleksandr, Oct 08 '16 at 08:44
umount -l will leave it mounted for processes that already have it open, but unmount it for all others. — Ole Tange, Oct 14 '16 at 10:52

score 1 · Accepted Answer · answered May 30 '17 at 21:43

It will be easier to use device mapper doing a linear remapping to the underlying disk and mounting from there as you can then simulate the disk crashing by switching device mapper to return the error target (e.g. through the use of dmsetup wipe_table). See https://unix.stackexchange.com/a/144200/134856 for this and other (such as using scsi_debug) disk error simulation techniques.

How to detach a disk in Linux (simulate a crash of partition/disk)?

1 Answers1