Device /sdb1 already mounted or mount pont busy

English Hardware
#1

I know this has been asked a zillion times, but you guys are nicer than other sites who’ll just flag it at DUPLICATE and blow me off.

I’ve got two drives - /sda is a 500G where I boot from, /sdb is a 250GB drive where I used to boot from. My laptop came with an M2 SSD only, which happened to be hard-coded as /dev/sdb. I added the 500GB drive later, and it slotted in and became /dev/sda. When I tried to set up a new OS (Kubuntu), it insisted on putting the bootloader on /dev/sda. I later found I could change that, but it’s too late for that.

So I got Tumbleweed (Krypton) installed on /dev/sda yesterday. But now I can’t get to /dev/sdb, which has some data on it that I carefully preserved.

The output of the relevant commands is as follows

/etc/fstab:

UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /                       btrfs  defaults                      0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /boot/grub2/x86_64-efi  btrfs  subvol=/@/boot/grub2/x86_64-efi  0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /boot/grub2/i386-pc     btrfs  subvol=/@/boot/grub2/i386-pc  0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /.snapshots             btrfs  subvol=/@/.snapshots          0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /var                    btrfs  subvol=/@/var                 0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /usr/local              btrfs  subvol=/@/usr/local           0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /tmp                    btrfs  subvol=/@/tmp                 0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /srv                    btrfs  subvol=/@/srv                 0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /root                   btrfs  subvol=/@/root                0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /opt                    btrfs  subvol=/@/opt                 0  0
UUID=d1b20c3b-a0bd-4e90-9836-929cf030c7c7  /home                   xfs    defaults                      0  0
UUID=cfd9456d-eba5-4a08-a5a4-3e06921a2f12  swap                    swap   defaults                      0  0

lsblk

NAME                                           MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda                                              8:0    0 465.8G  0 disk  
├─sda1                                           8:1    0     2M  0 part  
├─sda2                                           8:2    0   128M  0 part  
├─sda3                                           8:3    0   512M  0 part  
├─sda4                                           8:4    0    40G  0 part  
├─sda5                                           8:5    0 409.6G  0 part  
├─sda6                                           8:6    0  15.6G  0 part  
└─WDC_WDS500G2B0A-00SM50_174036423494          254:0    0 465.8G  0 mpath 
  ├─WDC_WDS500G2B0A-00SM50_174036423494-part1  254:2    0     2M  0 part  
  ├─WDC_WDS500G2B0A-00SM50_174036423494-part2  254:3    0   128M  0 part  
  ├─WDC_WDS500G2B0A-00SM50_174036423494-part3  254:4    0   512M  0 part  
  ├─WDC_WDS500G2B0A-00SM50_174036423494-part4  254:6    0    40G  0 part  /tmp
  ├─WDC_WDS500G2B0A-00SM50_174036423494-part5  254:7    0 409.6G  0 part  /home
  └─WDC_WDS500G2B0A-00SM50_174036423494-part6  254:8    0  15.6G  0 part  [SWAP]
sdb                                              8:16   0 238.5G  0 disk  
├─sdb1                                           8:17   0 238.5G  0 part  
└─HFS256G39TND-N210A_ES74N189710404M14         254:1    0 238.5G  0 mpath 
  └─HFS256G39TND-N210A_ES74N189710404M14-part1 254:5    0 238.5G  0 part  
sr0                                             11:0    1  1024M  0 rom

I want to end up with something straightforward like

/mnt/sdb1 -> /driveb

/dev/sdb1 has some code and scripts on it that I need to get back. What am I missing? is there some way I can recover what’s on /sdb1 and reformat that drive (if necessary)? But I can’t mount it. I’ve made a bunch of empty mount points (/driveb /devsdb1, etc) and it continually tells me it’s busy.

HALP!

#2

I don’t really have an answer for you. The problem seems related to that “mpath” appearing in the “type” column. That seems to indicate a multi-path device.

I don’t have experience with that. But I suggest you look at “/dev/mapper” to see if the device is logically mapped. If it is, them you probably have to mount the “/dev/mapper/whatever” mapped device instead of the physical device.

#3

Thanks. I’ll have to dig into /dev/mapper. To my unexperienced eye, it also looks like my /home directory has its own partition, using 400GB+ of space. Playing with partition tables is always risky, not to mention frustratingly slow.

#4

Boot what from?

#5

Kubuntu, until I added the second drive and decided to try something new.

#6

17.10? Was it your only OS? Was it using LVM? Does

lvmdiskscan

show any LVM physical volumes?

#7

It was actually 18.04 LTS, but it was my only OS.

lvmdisckscan reports:

sudo lvmdiskscan
[sudo] password for root: 
  /dev/mapper/WDC_WDS500G2B0A-00SM50_174036423494-part1         2.00 MiB] 
  /dev/mapper/WDC_WDS500G2B0A-00SM50_174036423494-part2       128.00 MiB] 
  /dev/mapper/WDC_WDS500G2B0A-00SM50_174036423494-part3       512.00 MiB] 
  /dev/mapper/WDC_WDS500G2B0A-00SM50_174036423494-part4        40.00 GiB] 
  /dev/mapper/WDC_WDS500G2B0A-00SM50_174036423494-part5       409.59 GiB] 
  /dev/mapper/WDC_WDS500G2B0A-00SM50_174036423494-part6        15.55 GiB] 
  /dev/mapper/HFS256G39TND-N210A_ES74N189710404M14-part1      238.47 GiB] 
  0 disks
  7 partitions
  0 LVM physical volume whole disks
  0 LVM physical volumes

fstab is:

sudo more /etc/fstab
[sudo] password for root: 
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /                       btrfs  defaults                      0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /boot/grub2/x86_64-efi  btrfs  subvol=/@/boot/grub2/x86_64-efi  0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /boot/grub2/i386-pc     btrfs  subvol=/@/boot/grub2/i386-pc  0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /.snapshots             btrfs  subvol=/@/.snapshots          0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /var                    btrfs  subvol=/@/var                 0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /usr/local              btrfs  subvol=/@/usr/local           0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /tmp                    btrfs  subvol=/@/tmp                 0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /srv                    btrfs  subvol=/@/srv                 0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /root                   btrfs  subvol=/@/root                0  0
UUID=c3701b53-9c69-4a81-a8d1-fc5ffabbe2c1  /opt                    btrfs  subvol=/@/opt                 0  0
UUID=d1b20c3b-a0bd-4e90-9836-929cf030c7c7  /home                   xfs    defaults                      0  0
UUID=cfd9456d-eba5-4a08-a5a4-3e06921a2f12  swap                    swap   defaults                      0  0
#8

… and now I get to learn the joys of a boot rescue CD, since I trashed GRUB trying to modify my partition table.

Luckily there’s a really good party planned for this afternoon and it’s a perfect spring day!

#9

Hopefully rescue will also fix your access problem. If not, as a workaround to recover the files you need from /sdb you could try a liveCD (or pendrive). There’s a Thumbleweed liveCD you can download, for example, and a lot of other more specialized distros.

#10

Multiple rescue discs did no good. Some because I have to boot in Legacy Mode (I.e. not EFI). Bloody cheap made-for-Windows laptops! Some other rescue solutions just croaked because they’re too old to speak btrfs.

So I might reduce the partition size on sdb and try pointing GRUB there, at least temporarily. It makes better sense to have my larger drive for storage anyway. One is an M2 format (sdb) and the additional one is a standard 2.5” (sda).

This is all very tedious, but it’s still better than the two full days I wasted trying to install Gentoo.

#11

Maybe try:

parted -l

The output might be lengthy. But it may tell you something about those “/dev/mapper/*” devices.

#12

Except now I have this slight problem:

https://makeagif.com/i/85YLiI

#13

Exactly when?

#14

At boot, after fooling with the partition table.

I swear, I’m smart in a whole lot of ways. Just none of them on display in this thread.

#15

Sounds like you’ve made impossible for an ordinary rescue boot to work, and need a utility that can reconstruct the partition table by finding boot sectors on disk. I only know of one, and it isn’t FOSS. I pay for the upgrade at every point release, and it’s worth it. It runs the same under all 4 well-known PC operating systems, and on Mac. It’s the only partitioner I ever allow to write to my many HD’s tables.

#16

Perhaps parted magic may interest you, then. It’s paid for (US$ 11,00 IINM, and worth it), can boot 32/64 bits, MBR/EFI, support a gazillion FS - btrfs included, boot to memory, and others. Nothing that other free rescue systems won’t do, but has all in one place, most utilities run from the xfce desktop, etc.
Just an idea.