How to re-mount the SD

guru · 23 Apr 2019, 11:05

Hello,

I can unmount my SD but can't mount it again with:

# mount
...
/dev/mmcblk1 on /media/phablet/A8FD-027E type vfat (ro,nosuid,nodev,relatime,uid=32011,gid=32011,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,showexec,utf8,flush,errors=remount-ro,uhelper=udisks2)
# umount /media/phablet/A8FD-027E
# mount /media/phablet/A8FD-027E
mount: can't find /media/phablet/A8FD-027E in /etc/fstab
# mount /dev/mmcblk1
mount: can't find /dev/mmcblk1 in /etc/fstab
# mount -t vfat /dev/mmcblk1 /media/phablet/A8FD-027E
mount: mount point /media/phablet/A8FD-027E does not exist
# ls -ld /media/phablet/A8FD-027E
ls: cannot access '/media/phablet/A8FD-027E': No such file or directory

What is the correct way to mount the SD again?

The background of my question is: every now and than files and dirs on my SD get corrupted. Is this a known problem?

tera · 23 Apr 2019, 13:28

@guru The target folder need to exist and permissions from the mounted filesystem will apply, try the following for example (note the partition at the end of sdcard device: ...p1):

sudo mount /dev/mmcblk1p1 /mnt

Did not have issue with corrupted files so far on FP2 but i'm using ext4 fs (now encrypted as well), but you can probably try to check the filesystem before mounting the partition:

sudo fsck.vfat /dev/mmcblk1p1

tera · 23 Apr 2019, 13:34

@guru You should also be able to use the following based on your input:

sudo fsck.vfat /dev/disk/by-uuid/A8FD-027E
sudo mount /dev/disk/by-uuid/A8FD-027E /mnt

guru · 23 Apr 2019, 15:33

I have 30+ years of UNIX knowlege and know how to mount a fs. The question was, how to mount it again exactly as done by UT on boot or by the app after formatting.

tera · 23 Apr 2019, 17:12

@guru That bumps it up to almost 60 years on this page, hopefully we will manage
Looking at https://github.com/ubports/ciborium, it seems that udisks2 is in use, can you have a try with something like this (maybe without p1):

sudo udisksctl mount -b /dev/mmcblk1p1

Never heard ab it before tbh, info seems to give hints as well: http://manpages.ubuntu.com/manpages/xenial/man1/udisksctl.1.html

guru · 24 Apr 2019, 06:59

@tera said in How to re-mount the SD:

@guru The target folder need to exist and permissions from the mounted filesystem will apply, try the following for example (note the partition at the end of sdcard device: ...p1):
sudo mount /dev/mmcblk1p1 /mnt
Did not have issue with corrupted files so far on FP2 but i'm using ext4 fs (now encrypted as well), but you can probably try to check the filesystem before mounting the partition:
sudo fsck.vfat /dev/mmcblk1p1

Is ext4 on the SD supported without making the system writable to modify the fstab?

tera · 24 Apr 2019, 08:09

@guru said in How to re-mount the SD:

Is ext4 on the SD supported without making the system writable to modify the fstab?

I would guess not, using encryption, a script is required to mount the fs following this post: https://forums.ubports.com/topic/1012/one-method-to-encrypt-home-phablet

I had a go at it, inserted a new SD card, formatted it using the External Drives app and it actually do not create a partition but format the whole SD card in fat32/vfat which is a behavior i have never observed before...

Additional 2p, it looks like the External Drives app only support vfat:
https://github.com/ubports/ciborium/blob/xenial/cmd/ciborium/main.go#L107
https://github.com/ubports/ciborium/blob/xenial/cmd/ciborium-ui/main.go#L53