[Mi 3 Original Android Development] allefarben:
Manually mounting in recovery mode does the same:

./adb shell mount /dev/block/platform/msm_sdcc.1/by-name/userdata /data
mount: mounting /dev/block/platform/msm_sdcc.1/by-name/userdata on /data failed: No such file or directory

The userdata refers to /dev/block/mmcblk0p25 and when I look into /dev/block:

./adb shell ls -l /dev/block
__bionic_open_tzdata: couldn't find any tzdata when looking for localtime!
__bionic_open_tzdata: couldn't find any tzdata when looking for GMT!
__bionic_open_tzdata: couldn't find any tzdata when looking for posixrules!
brw------- 1 root root 7, 0 Mar 21 20:04 loop0
brw------- 1 root root 7, 1 Mar 21 20:04 loop1
brw------- 1 root root 7, 2 Mar 21 20:04 loop2
brw------- 1 root root 7, 3 Mar 21 20:04 loop3
brw------- 1 root root 7, 4 Mar 21 20:04 loop4
brw------- 1 root root 7, 5 Mar 21 20:04 loop5
brw------- 1 root root 7, 6 Mar 21 20:04 loop6
brw------- 1 root root 7, 7 Mar 21 20:04 loop7
brw------- 1 root root 179, 0 Mar 21 20:04 mmcblk0
brw------- 1 root root 179, 1 Mar 21 20:04 mmcblk0p1
brw------- 1 root root 179, 10 Mar 21 20:04 mmcblk0p10
brw------- 1 root root 179, 11 Mar 21 20:04 mmcblk0p11
brw-rw---- 1 system system 179, 12 Mar 21 20:04 mmcblk0p12
brw-rw---- 1 system system 179, 13 Mar 21 20:04 mmcblk0p13
brw------- 1 root root 179, 14 Mar 21 20:04 mmcblk0p14
brw------- 1 root root 179, 15 Mar 21 20:04 mmcblk0p15
brw------- 1 root root 179, 16 Mar 21 20:04 mmcblk0p16
brw------- 1 root root 179, 17 Mar 21 20:04 mmcblk0p17
brw------- 1 root root 179, 18 Mar 21 20:04 mmcblk0p18
brw------- 1 root root 179, 19 Mar 21 20:04 mmcblk0p19
brw------- 1 root root 179, 2 Mar 21 20:04 mmcblk0p2
brw------- 1 root root 179, 20 Mar 21 20:04 mmcblk0p20
brw------- 1 root root 179, 21 Mar 21 20:04 mmcblk0p21
brw------- 1 root root 179, 22 Mar 21 20:04 mmcblk0p22
brw------- 1 root root 179, 23 Mar 21 20:04 mmcblk0p23
brw------- 1 root root 179, 24 Mar 21 20:04 mmcblk0p24
brw------- 1 root root 179, 3 Mar 21 20:04 mmcblk0p3
brw------- 1 root root 179, 4 Mar 21 20:04 mmcblk0p4
brw------- 1 root root 179, 5 Mar 21 20:04 mmcblk0p5
brw------- 1 root root 179, 6 Mar 21 20:04 mmcblk0p6
brw------- 1 root root 179, 7 Mar 21 20:04 mmcblk0p7
brw------- 1 root root 179, 8 Mar 21 20:04 mmcblk0p8
brw------- 1 root root 179, 9 Mar 21 20:04 mmcblk0p9
brw------- 1 root root 179, 32 Mar 21 20:04 mmcblk0rpmb
drwxr-xr-x 3 root root 60 Mar 21 20:04 platform
brw------- 1 root root 1, 0 Mar 21 20:04 ram0
brw------- 1 root root 1, 1 Mar 21 20:04 ram1
brw------- 1 root root 1, 10 Mar 21 20:04 ram10
brw------- 1 root root 1, 11 Mar 21 20:04 ram11
brw------- 1 root root 1, 12 Mar 21 20:04 ram12
brw------- 1 root root 1, 13 Mar 21 20:04 ram13
brw------- 1 root root 1, 14 Mar 21 20:04 ram14
brw------- 1 root root 1, 15 Mar 21 20:04 ram15
brw------- 1 root root 1, 2 Mar 21 20:04 ram2
brw------- 1 root root 1, 3 Mar 21 20:04 ram3
brw------- 1 root root 1, 4 Mar 21 20:04 ram4
brw------- 1 root root 1, 5 Mar 21 20:04 ram5
brw------- 1 root root 1, 6 Mar 21 20:04 ram6
brw------- 1 root root 1, 7 Mar 21 20:04 ram7
brw------- 1 root root 1, 8 Mar 21 20:04 ram8
brw------- 1 root root 1, 9 Mar 21 20:04 ram9
brw------- 1 root root 253, 0 Mar 21 20:04 zram0
brw------- 1 root root 253, 1 Mar 21 20:04 zram1
brw------- 1 root root 253, 2 Mar 21 20:04 zram2
brw------- 1 root root 253, 3 Mar 21 20:04 zram3

There is no mmcblk0p25!

But I have a mounting from /dev/userdata_moved to /data_root

./adb shell mount
rootfs on / type rootfs (rw)
tmpfs on /dev type tmpfs (rw,seclabel,nosuid,relatime,size=931552k,nr_inodes=175218,mode=755)
devpts on /dev/pts type devpts (rw,seclabel,relatime,mode=600)
proc on /proc type proc (rw,relatime)
sysfs on /sys type sysfs (rw,seclabel,relatime)
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)
tmpfs on /tmp type tmpfs (rw,seclabel,relatime,size=931552k,nr_inodes=175218)
tmpfs on /storage type tmpfs (rw,seclabel,relatime,size=931552k,nr_inodes=175218,mode=050,gid=1028)
tmpfs on /mnt/secure type tmpfs (rw,seclabel,relatime,size=931552k,nr_inodes=175218,mode=700)
tmpfs on /mnt/fuse type tmpfs (rw,seclabel,relatime,size=931552k,nr_inodes=175218,mode=775,gid=1000)
/dev/userdata_moved on /data_root type ext4 (rw,seclabel,nodev,noatime,nodiratime,data=ordered)
/dev/block/platform/msm_sdcc.1/by-name/cache on /cache type ext4 (rw,seclabel,nodev,noatime,nodiratime,data=ordered)

Inside the /data_root it looks like this:

./adb shell ls -l /data_root
__bionic_open_tzdata: couldn't find any tzdata when looking for localtime!
__bionic_open_tzdata: couldn't find any tzdata when looking for GMT!
__bionic_open_tzdata: couldn't find any tzdata when looking for posixrules!
drwx------ 2 root root 4096 Mar 8 16:03 adb
drwxrwx--x 2 system system 4096 Mar 8 16:03 app
drwx------ 2 root root 4096 Mar 8 16:03 app-asec
drwxrwx--x 2 system system 4096 Mar 8 16:03 app-lib
drwxrwx--x 2 system system 4096 Mar 8 16:03 app-private
drwxrwx--- 2 media audio 4096 Mar 8 16:03 audio
drwx------ 4 system system 4096 Mar 8 16:05 backup
lrwxrwxrwx 1 root root 45 Mar 8 16:03 bugreports -> /data/data/com.android.shell/files/bugreports
srwxrwx--- 1 camera camera 0 Mar 17 17:11 cam_socket1
srwxrwx--- 1 camera camera 0 Mar 17 17:11 cam_socket2
drwxrwx--x 3 system system 4096 Mar 8 16:03 connectivity
drwxrwx--x 4 root root 4096 Mar 8 16:03 dalvik-cache
drwxrwx--x 82 system system 4096 Mar 8 16:04 data
drwxr-x--- 2 root log 4096 Mar 8 16:03 dontpanic
drwxrwx--- 2 drm drm 4096 Mar 8 16:03 drm
-rw-rw---- 1 camera camera 1780 Mar 8 16:08 fdAlbum
drwxrwx--x 2 system system 4096 Mar 8 16:03 fota
drwxrwx--- 2 system wifi 4096 Mar 8 16:03 hostapd
drwxr-x--x 3 root root 4096 Mar 8 16:03 local
drwxrwx--- 2 root root 4096 Mar 8 16:03 lost+found
drwxrwx--- 6 media_rw media_rw 4096 Mar 13 20:05 media
drwxrwx--- 2 mediadrm mediadrm 4096 Mar 8 16:03 mediadrm
drwxrwx--t 28 system misc 4096 Mar 8 16:03 misc
drwxrwx--- 3 nfc nfc 4096 Mar 8 16:03 nfc
drwx------ 2 root root 4096 Mar 17 17:11 property
drwxrwx--x 2 system system 4096 Mar 8 16:03 resource-cache
drwx--x--x 2 system system 4096 Mar 8 16:03 security
drwxr-xr-x 2 system system 4096 Mar 8 16:03 shared
drwxrwxr-x 20 system system 4096 Mar 21 19:41 system
drwx------ 2 system system 4096 Mar 8 23:03 time
drwxrwx--x 6 system system 4096 Mar 8 16:07 tombstones
drwx--x--x 2 system system 4096 Mar 8 16:03 user

Is this the place i should copy sfos?