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Old 10-28-2013, 10:30 AM   #1
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Registered: Sep 2013
Posts: 23

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LUKS- /dev/mapper/"device" disappears after reboot

I successfully created LUKS on one disk partition of /dev/sdb,
added entry to /etc/fstab and mounted. It was fine.
I edited /etc/crypttab and added

mountpt /dev/sdb none

When booting it asks for passphrase and then is mounted.
Thats fine.
According to all sources /etc/crypttab can seem like:

mountpt /dev/mapper/device

But when I put it like that it doesnt mount and send error that /dev/mapper/device doesn't exists
It works only when put phisical entry /dev/sdb.
I'm confused

Last edited by makupl; 11-05-2013 at 02:28 AM. Reason: more tests done
Old 10-25-2017, 07:36 AM   #2
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Registered: Oct 2017
Posts: 1

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Unhappy LUKS /dev/mapper/<device name> disappears after reboot (Linux Deepin)


I'm facing the same issue here, under Linux Deepin. It started after a apt-get dis-upgrade. Tried to reinstall the OS and reconfigure the encrypted device as /home. It works OK until next reboot, when OS enters in recovery mode. A "ls /dev/mapper" confirms the device no longer exists and I have to run a "cryptsetup luksOpen /dev/sda3 <UUID>" all over again to make it work. It's annoying!

Any ideas on how to solve that?

Thanks a lot!

Best regards,

Luis Talora
Old 10-25-2017, 08:03 AM   #3
Registered: Aug 2017
Location: Terra Mater
Distribution: VM Host: Slackware-current, VM Guests: Artix, Venom, antiX, Gentoo, FreeBSD, OpenBSD, OpenIndiana
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I do not mount luks encrypted partition at boot time. I mount it when I need it but you can add this:

/dev/mapper/crypt /mnt/encrypted ext4 discard,noatime,errors=remount-ro 0 1

it means that you have to create manually /mnt/encrypted mount point
it assumes that your luks encrypted device is formatted with ext4 and that it is on ssd (discard option if you don't care so much about possible trimming leakage)

this is my /etc/crypttab
encrypted UUID=xxxxxxxxxxxxxxxxxxx none luks,discard

UUID info from blkid
I think that you don't need to edit /etc/crypttab anymore (maybe distro specific though)

manually mount luks device
sudo cryptsetup --type luks --allow-discards open /dev/sdbX encrypted

where /dev/sdbX
corresponds to the partition number that is encrypted and command above assumes ssd ready for fstrim

next mount ext4 partition:
#sudo mount -t ext4 /dev/mapper/encrypted /mnt/encrypted/

after you mount luks device/ext4 partition you should see:

sudo cryptsetup status /dev/mapper/encrypted
/dev/mapper/encrypted is active and is in use.
type: LUKS1
cipher: aes-xts-plain64
keysize: 512 bits
device: /dev/sdb1
offset: 4096 sectors
size: 184315904 sectors
mode: read/write
flags: discards

hope this will help a bit


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