Arch Linux

spongycrumb

Member

Registered: 2021-05-23

Posts: 4

[SOLVED] luks btrfs raid1 problem, polkit prompts for 2nd disk at boot

Hello,

In my computer I have 2 hard disks, separate to the drive on which I have arch installed, each of which I encrypted using dm-crypt using the command (where device was replaced by /dev/sdX as appropriate):

 # cryptsetup luksFormat device 

I then unlocked both of those using luksOpen, partitioned them using parted (each as one single partition) and then used mkfs to create a btrfs raid 1 filesystem across the two disks

 # mkfs.btrfs -m raid1 -d raid1 /dev/mapper/cryptdrive1 /dev/mapper/cryptdrive2 

cryptdrive1/2 are my chosen device mapper names for the two disks. From this I got an output with one single UUID for the whole filesystem covered both disks which was 8b5b8a33-79dc-48cb-a5ae-b12946098ec0

In the /etc/fstab file I have the UUID for the btrfs system (to be mounted at /data) rather than two separate entries for each physical storage devices used to create the filesystem, i.e. in /etc/fstab I added the following line

 UUID=8b5b8a33-79dc-48cb-a5ae-b12946098ec0    /data             btrfs   defaults   0 0

Both drives are luks encrypted volumes so they also need to be unlocked prior to mounting the filesystem so to do that I use /etc/crypttab where I have the following lines (the passphrase.txt is the file on the root filesystem /etc directory in which I store the passphrase):

cryptdrive1     UUID=f6fe18ca-4f92-49eb-b775-84315ef292ee        /etc/passphrase.txt
cryptdrive2     UUID=d40251bf-9bdc-4298-abd6-8380a9675ccd        /etc/passphrase.txt

the UUIDs in the crypttab file are the ones for the physical drives themselves as reported by the blkid command

This all works as I expected with the btrfs filesystem loaded automatically and functioning as normal apart from one problem I have been unable to resolve. Each time I login to my desktop environment I get a pop up box "Authentication is required to mount /dev/mapper/cryptdrive2"  which is from "PolicyKit1 KDE Agent".  I am running KDE Plasma desktop environment with SDDM as my display manager.  This notification appears after I enter my password to log in to my user account and the KDE desktop loads. There are no problems functionally with the btrfs raid 1 setup. I can simply press cancel on the notification and ignore it but I'd like to solve the problem properly to stop it appearing.

I don't understand why the second drive is trying to mount or how to suppress this notification. Clearly I've done something wrong, can anyone guide me in the right direction please?

Last edited by spongycrumb (2021-05-23 17:35:29)

spongycrumb

Member

Registered: 2021-05-23

Posts: 4

Re: [SOLVED] luks btrfs raid1 problem, polkit prompts for 2nd disk at boot

I should have read the wiki more carefully before posting- solution is here: https://wiki.archlinux.org/title/Udisks … partitions

create a udev rule in /etc/udev/rules.d and tell it to ignore the UUID of the second disk in the btrfs filesystem