Database Users

Partitioning microSD card

After setting up my wife's A7 and using it for three weeks, I have decided to open mine up. I waited because I wanted to see if CES had anything I wanted more. I decided they didn't.
So, I am starting from scratch again.
The main issue I've had with my wife's A7 has been the lack of storage space for apps, especially the big games.
Bazbob seems to have a solution by partioning the microSD card and using Apps2sd.
I took a new Class 10 16GB microSD card.
I downloaded and burned Ubuntu onto a CD from here: http://www.ubuntu.com/desktop/get-ubuntu/download
Put the card in my laptop, restarted it into Ubuntu.
Ran gparted.
Shrunk the Fat32 partition to just under 8GB and added another partion as ext2 primary.
When I restarted my laptop, my sd reader in the laptop doesn't work.
When I put it into the A7, it says the SD card has Total Space of 7.73GB.
At this point, I'm not sure what to do next.
Help is appreciated!

jazzbone said:
After setting up my wife's A7 and using it for three weeks, I have decided to open mine up. I waited because I wanted to see if CES had anything I wanted more. I decided they didn't.
So, I am starting from scratch again.
The main issue I've had with my wife's A7 has been the lack of storage space for apps, especially the big games.
Bazbob seems to have a solution by partioning the microSD card and using Apps2sd.
I took a new Class 10 16GB microSD card.
I downloaded and burned Ubuntu onto a CD from here: http://www.ubuntu.com/desktop/get-ubuntu/download
Put the card in my laptop, restarted it into Ubuntu.
Ran gparted.
Shrunk the Fat32 partition to just under 8GB and added another partion as ext2 primary.
When I restarted my laptop, my sd reader in the laptop doesn't work.
When I put it into the A7, it says the SD card has Total Space of 7.73GB.
At this point, I'm not sure what to do next.
Help is appreciated!
Click to expand...
Click to collapse
You needed to make a second partition EXT2 and format it. You then need to mount the partition. I did this by using the install-recovery.sh that it located in /system/etc. I used the following tutorial and it worked. I got over 12gb of space to install apps.
http://forum.xda-developers.com/showthread.php?t=832799
I did try to mount the new partition to /storage which is also /sdcard and i was still not able to use titanium backup to move apps. The only way i have alot of space is use this method.
I'm also mounting the fat32 partition to location /storage so that when i download apps thats where they are stored until you install them. Also Titanium backup dumps the backups here. This is done with a custom mod of Dexters 1.0c mod.
I did not use adb, i used a app called quicksshd which allows you secure ftp into the tablet and make changes. I suggest using a windows programs called winscp and putty.

Thanks for replying rfisher.
Turns out that my laptop lost the drive letter for the sd card. That's fixed now. When I insert the card into my laptop, it says that you need to format the card in the drive to use it. Any idea why?
I am confused by your instructions.
You said
You needed to make a second partition EXT2 and format it.
Click to expand...
Click to collapse
I did that. First partition is FAT 32, and second partition is EXT2, primary.
Maybe I didn't format the partition? I just created it.
I'll install busybox and see how far I can get with it.
With the other A7, I was never able to work with ADB.
This device really makes me feel like an idiot.
Still can't believe I was the first to get Google Apps working on my wife's tablet!

no adb
Well, the hours of frustration have returned...
I can't get adb running on my laptop.
I installed Android SDK.
When I type adb in the cmd window on my laptop, I get
"adb" is not recognized as an internal or external command, operable program or batch file"
I have tried moving the ADK folder to c:\
and
to:
C:\Users\Bucks HP
No luck.
I added the path c:\android-sdk-windows\platform-tools
to the environment variables in my system properties.
My head is going to explode!

Well, I got adb working, I think...
Problem was in the cmd window. I had to change the path.
Now, I can't install busybox. I followed the instructions from the wiki.
When I type "adb push busybox /data/local"
it returns: cannot stat 'busybox' : no such file or directory.
I pasted the busybox file in the
C:\android-sdk-windows\platform-tools
folder.
Was that the right place for it?
Is the busybox file just a text file?
Also, mine is named busybox-armv6l
Should it be renamed? I tried "adb push busybox-armv6l /data/local"
and got the same result...

I gave up on installing busybox via the wiki instructions.
I installed Titanium Backup and installed busybox through it.
Now, when I type: cd /system
mkdir sd
I get :
mkdir failed for sd, read-only file system
What does that mean and how do I fix it?
Thanks

The saga continues...
With the busybox from Titanium Backup installed,
I needed to type:
adb shell
su
mount -o remount,rw /dev/block/mmcblk3p1 /system
exit
exit
Then, following the tutorial, I am up to step 12:
12) Now comes the tricky part: making Android mount your new partition at boot time. All the hard work would be useless if Android discarded the mount points every time we restarted our phones. To do this we’ll need to create 2 scripts and store then into /system/etc. Obviously the scripts should be started by init.rc and need to run as root. Fortunately Android’s init.rc have a gap that makes this possible. The scripts are named install-recovery.sh and init-sd2.sh.
My question is: How do you create scripts?

You would create them with notepad++ which is a windows program. Then using adb push them to the /system/etc directory.
I used a app called quicksshd and a windows program called winscp to copy the files to the directory. If you used my method you first need to make the /system directory rw before it will let you copy the files. It worked for me, the only thing i did differently is edit init.rc to mount the first partition of the sd card to /storage, but this was creating a modded 1.0c rom. So the result is about 4gb for my sd memory and 12gb for installing apps.
jazzbone said:
The saga continues...
With the busybox from Titanium Backup installed,
I needed to type:
adb shell
su
mount -o remount,rw /dev/block/mmcblk3p1 /system
exit
exit
Then, following the tutorial, I am up to step 12:
12) Now comes the tricky part: making Android mount your new partition at boot time. All the hard work would be useless if Android discarded the mount points every time we restarted our phones. To do this we’ll need to create 2 scripts and store then into /system/etc. Obviously the scripts should be started by init.rc and need to run as root. Fortunately Android’s init.rc have a gap that makes this possible. The scripts are named install-recovery.sh and init-sd2.sh.
My question is: How do you create scripts?
Click to expand...
Click to collapse

Hi rfisher
Thanks for replying!
While waiting, I opened Notepad++, copied the text in the tutorial window into it and saved the file as Unix.
Then, I copied it to a USB drive, put it in the A7, and copied to the system/etc folder.
Is that acceptable?
Then, I followed steps 13-15.
I think I did something wrong. I am not seeing it in Root Explorer. What should I be looking for?
Was I supposed to install Apps2SD already?
I got winscp and quicksshd working. YEAH!
Used them to copy the files as you did.
Restarted A7.
Still don't see the other partition.
PS. I was just rereading your earlier post and you mentioned:
I did try to mount the new partition to /storage which is also /sdcard and i was still not able to use titanium backup to move apps. The only way i have alot of space is use this method.
I'm also mounting the fat32 partition to location /storage so that when i download apps thats where they are stored until you install them. Also Titanium backup dumps the backups here. This is done with a custom mod of Dexters 1.0c mod.
Looking on my A7, I don't see a location that is /storage
My tablet is fresh out of the box, without any firmware updates yet.

[Q] Redirect mount point of External SD..

Can I change the mount point of the External SD card (microsd) from
/mnt/external_sd
to
/mnt/sdcard/MicroSD
I tried changing the entry in vold.fstab to no help. it wasn't mounted to /mnt/external_sd but it also wasn't mounted to the MicroSD folder i made on /mnt/sdcard
This would let any program that doesn't have the ability to handle the external SD card to be able to access it as it wouldn't know where it was. I could then do this to USB drives plugged in as well.

Nova5 said:
Can I change the mount point of the External SD card (microsd) from
/mnt/external_sd
to
/mnt/sdcard/MicroSD
I tried changing the entry in vold.fstab to no help. it wasn't mounted to /mnt/external_sd but it also wasn't mounted to the MicroSD folder i made on /mnt/sdcard
This would let any program that doesn't have the ability to handle the external SD card to be able to access it as it wouldn't know where it was. I could then do this to USB drives plugged in as well.
Click to expand...
Click to collapse
This might not exactly be the route you wanna take, but have you tried adding a symlink? Might do the trick, then again, I'm having a little issue with the same thing right now. Looks like this has been a popular subject lately

symlinks seem to be inoperable in HC.
Found this on another forum
Have you tried "bind" mounting?
Doesn't wok for me as I have a stock (unrooted) transformer...
cd /mnt/sdcard
mkdir MicroSD
mount -o bind /mnt/external_sd /mnt/sdcard/MicroSD
Click to expand...
Click to collapse
Works fairly well. Doesn't effect the storage count for the internal memory however. if we could actually mount it to a folder inside the scdard mount then it may show up as extra space, but i kinda doubt that bit.

Those system files are overwritten on each reboot so you have to "mount -o bind" on every reboot.
If you find a way to make this mount point permanent let me know, I am looking for a way as well.

If you're rooted, I think USB Mount All did this.

powercat_ said:
Those system files are overwritten on each reboot so you have to "mount -o bind" on every reboot.
If you find a way to make this mount point permanent let me know, I am looking for a way as well.
Click to expand...
Click to collapse
What system files? Its simply a mount point created and handled in memory. its never added to a file. I forget what the start up command file is in linux that is the sister of DOSs Autoexec.bat. It would need to be added to that as the last command. Now i have read this is a risky command to run as it can create a endless loop if something attempts to scan the directories it can run into a recursive loop. Now I believe this is because most instances of this command tend to be used to bring a directory onto the desktop thats a few steps above it. Considering that the way I am using it is to link a directory that is outside the scope of another, it shouldn't ever cause this and be a pretty safe way to do it. The BIND command creates a hard link between the two locations. the /mnt/sdcard/MicroSD is a directory I created. when I bind it to the /mnt/external_sd directory the files appear in both places at the same time as MicroSD is simply a... tunnel as it were into External SD. But the programs are convinced its MicroSD. So those that can't use the external sd slot now can through this "tunnel". The same trick can also be applied to the directory for the USB thumb/flash drives.
Just create a directory for it on /mnt/sdcard

fermunky said:
If you're rooted, I think USB Mount All did this.
Click to expand...
Click to collapse
why pay when you can enter a command and its done?

Yes, mount -o bind works, but if you reboot, the mount point is no longer there.
Sure, we can add an entry to fstab, but the file is overwritten by a reboot
the autostart file is init.rc, which is overwritten by a reboot as well, so that rules out using it to auto mount this bind.
let me know if you find other information as I would very much like this to work.
FYI I started a thread about this command a few days back but never got any pertinent information:
http://forum.xda-developers.com/showthread.php?t=1287522
(this was before 3.2 when you couldn't access the SD card from usb)

Nova5 said:
why pay when you can enter a command and its done?
Click to expand...
Click to collapse
Because it is only a few bucks, and it will do it for you without having to manually do it. I know it's quite a simple task, but I say best out of sight/out of mind.

its overwrites those huh? that bites..

fermunky said:
Because it is only a few bucks, and it will do it for you without having to manually do it. I know it's quite a simple task, but I say best out of sight/out of mind.
Click to expand...
Click to collapse
Just takes a bit to track where we can stick the commands to get an auto start. I may make a simple script file to leave on the home screens. tap and done.

Okay it seems the location where the init.rc is stored is volatile. I created a test file in there and rebooted the tablet, file is gone. So its less overwriting and simply copying out of its hidden location to a usable one. sdcard in there is just a mount point for the actual hardware address location of the sdcard. So if we want to get the autostart we would have to discover where HC pulls that data from on boot.

Bind will fail if the location that actually holds the data is not present/ready. usb_storage is more affected by this as a user doesn't normally leave a flash drive in the port. Script manager can auto-execute a script on boot. Works well enough.
hmm...
It appears if you remove the usb drive after making the bind, the bind is broken. So while its workable, its not perfect. Of course since the microsd card is rarley removed, this isn't much of an issue. If we could get the script to also run on insertion of the USB drive that would then make it work better.
SCript Manager allows one to create a direct shortcut to execute a specific script. So you can swap USB drives, tap the script icon and then access the script through the bound directory.

I use the following program created by RubberBigPepper from an alternative russian site about android apps and devices.

Any interesting effect I've noticed, any time the script runs it creates a new mount entry for the bind command, even if that bind already exists. OfficePro5 shows this by listing MicroSD for each bind entry. So I had 13 entries of MicroSD as it ran that many times, due to a setting I shouldn't have checked... Run on Net Change. But it pointed out this interesting effect.

I now see the need for this as one of my apps does not natively see the ext sd card.
OK I tried the apk above and it does not seem to work. I get a folder called ex_sdcard but it is empty and does not reflect the sd card contents.
Nova, you found another way yet you could share, or do I just need to manually create symlinks after every boot?

mountmicrosd.sh
Code:
# Note : Super user required. Your Tablet MUST be rooted!
# Removing the card will disrupt the bind. And Require running script again when plugged back in.
echo Breaks any existing Bind mount to avoid creating duplicate Bind entries. a "failed" response is acceptable as is no response.
umount /mnt/sdcard/MicroSD
echo execute Micro SD mount - card must be plugged in or Invalid Argument error will occur.
mount -o bind /mnt/external_sd /mnt/sdcard/MicroSD
Place the above in a text file with the extension .sh Download from the Market a program called Script Manager. Place the sh file in your SD card root. Run script manager, select that file and check two boxes. Run on Boot, Run as Root. Also create the directory of "MicroSD" Just as its typed. Linux is very caps sensitive. now every time you boot it will automatically run the script and bind the ExSD to the MicroSD directory.
This one will do the USB drive.
mountusb.sh
Code:
# Note : Super user required. Your Tablet MUST be rooted!
# Removing the drive will disrupt the bind. And Require running script again when plugged back in.
echo Breaks any existing Bind mount to avoid creating duplicate Bind entries. a "failed" response is acceptable as is no response.
umount /mnt/sdcard/USBDrive
echo execute USB Drive mount - drive must be plugged in or Invalid Argument error will occur.
mount -o bind /mnt/usb_storage /mnt/sdcard/USBDrive
Create a widget with ScriptManager to have a touchable icon on your screen to run this one. Note it must have the folder "USBDrive" created on the sdcard.
It is unimportant if you use the same filename.sh i did. That is just so I knew at a glance what it does. # is a comment and Echo prints the text following it to the screen. I found a way around the mutiple bind entries by simply unmounting it before making the mount bind. You might see a Failed error, this is just fine. it just means there was no mount for it to undo on its first run. this will be more helpful on the USB drive script than the MicroSD card one.

Very cool, Nova5!
Thanks for taking the time to research it further.
I tested your solution and it works fine!

I updated it with a fix to prevent the multiple entries. You'll need to update your files to reflect the changes I made. a reboot will be the simplest way to ensure it starts with a clean slate. Notice I removed the comment about Running it once only, due to the umount command preceeding the mount command. This removes the bind from memory and then when its created again you don't have the problem of 13 entries of MicroSD in OfficePro like I ran into.
Alright, I think its as good it is going to get. You could put them in the same files but for simplicity and being able to swap USB drives without affecting the ExSD card two files is best.
Wait... debug time. I goofed something.
Okay fixed up and working right. Remember what I mentioned about linux and capitals? oops. Echo is not echo.

Shucks, im not rooted.

howto: mount external sdcard as sdcard0

So, the Note 8.0 is a nice, fast, expensive device that had a big shortcoming for me: as shipped, the SD card is not useful as a place where application data easily lands - it's only intended for storing music and video files, or those chunks of data you manually target to it.
I fixed it, after a fashion, by mounting the card at boot time as sdcard0, which Samsung normally assigns to the (very limited) internal storage. The internal /data/media pool is treated as the external sdcard and very little installation data defaults to it. Apps2SD is still broken, but quite a lot of things simply default to using /sdcard0 as their preferred storage, which I find helpful.
You have to mount it at start time (init.d), and you have to mount it correctly (bind)
I figured out and set my device up this way by setting init.d scripts I learned about from threads by Ryuinferno (init.d) and mattiadj (rebinding in the Note 2) for this. Translation: none of this is my work, I just sounded out how others had done it and am assembling it here, since I know it will help other Note 8 folks.
I think that the init.d script support is very interesting - there are a lot of ROM tweaks that rely on init.d. You do not need a custom kernel for init.d to work the note 8 - which is nice, since we have no custom kernel
The outcome of this mod is that with an sdcard inserted, I get:
/storage/sdcard0 29.7G 3.68G 26.0G 32768
and
/storage/extSdCard 9.87G 1.78G 8.09G 4096
If I remove the card at boot, I still have apps (installed at /data/data) and the media
pool reverts to normal:
/storage/sdcard0 9.78G 1.78G 7.99G 4096
I wrote none of the scripts I'm using and will be the first to admit that I may have set them up stupidly.
Doing this voids your warranty and gives you pimples and a moon tan. But it does mean your sd card expands your storage and I hope that if there are better ways to do any of this, folks will chime in.
tools needed:
- knowledge of ADB and working ADB
- helps if you know how Unix and windows terminate lines differently, and can get your copy of Notepad++ to help you with the script, if you're trying this from Windows
- a note 8 running the 4.1.2 software - this approach is only tested there
- Kies
- Possibly Odin as a replacement for Kies (untested)
- understanding of how to put your device into recovery mode and trigger the Samsung recovery
- the US stock firmware for your device, for use with Odin (unless waiting on 1+ gig downloads if you screw something up is ok by you - the Kies method works, slooooowly.)
- Framaroot, to root your Note 8 (see the thread by tweebee)
- Busybox installed
Steps:
Install Framaroot
Root your device
Install busybox
Easy part done.
Next, you need to be able to run init.d scripts. At first I thought this might require a custom kernel, until I ran into Ryuinferno's excellent tool for enabling init.d without a custom kernel.
the thread I learned this from is by Ryuinferno at http://forum.xda-developers.com/showthread.php?t=1933849
I used term-init.sh from an ADB command line, but the thread has an APK in it called Uni-Init.apk that I would expect to work.
What you're doing is creating an install-recovery.sh script and telling it to go read /etc/init.d and run scripts there at boot.
Next, you want to create a simple script and drop it into /etc/init.d You can do this with an adb push; if you create the file in windows, though, you need to deal with the line endings correctly. You need the script to be executable and to be owned by root.
The one I'm using is this, from Mattiadj of the Note 2 community
in this thread: http://forum.xda-developers.com/showthread.php?t=2036796:
I call the script 07mount on my device, and a copy is attached to this post.
-----------------------script starts next line
#!/system/bin/sh
#extsd2internalsd is a modification that allows to switch internal sd to external sd
#and viceversa. With this you can use default internal sd only for app storage
#and the external sd to store all apps resource and all others stuff. The resut is a very
#big increase of installable apps on gnote2 and note8
#All credits to Mattiadj of xda forum for the idea and script and to mike1986 for
#the cmw zip. xda thread url
# at http://forum.xda-developers.com/showthread.php?t=2036796:
sleep 10
mount -o remount,rw /
mount -t vfat -o umask=0000 /dev/block/vold/179:17 /storage/sdcard0
sleep 30
mount -o bind /data/media /storage/extSdCard
chmod 777 /mnt/extSdCard
sleep 10
chown 1023:1023 /storage/extSdCard
chown 1000:1000 /storage/sdcard0
------------- end script on blank line above
You need /system remounted read/write, either in your favorite file explorer or via adb shell:
#mount -o rw,remount /system
to put the file in and
#chown root:root
the script itself
Now, put a fat32 formatted card into your sdcard, and reboot. When done, you should be able to see that your data storage has been remapped.
If you ever wanted to install a Samsung update, by the way, you'd need to completely unroot the device. I think the following would probably work:
- remove the su binary
- remove superuser from /system
- remove the busybox binaries
- remove install-recovery.sh from /etc and the /etc/init.d folder
If there was someting in an update you really wanted, you might do better to start by using the Samsung firmware downloaded from samfirmware.com, set your device all the way back to a clean install, then check for the OTA - Samsung does look at modifications and blocks updates to devices with changes to /system. My device is ineligible for OTA at this time.
That said, it appears that using Kies in emergency recovery mode can be used to reset your device to an as-shipped condition (I learned this when an early experiment resulted in my device being weirdly screwed up - bootable, but the network was down for the browser, etc. DNS and ping worked from an ADB prompt, though...)
You can download a copy of the script at http://www.mediafire.com/?2wbm439vlapb6om

I'm gonna try this when I have a full afternoon off as I tend to mess things up the first time I do them. But this will be super useful if I get it working. Hopefully when people start developing custom roms they can build this script in and save us all the trouble :highfive:

Haven't tried it yet, but it sounds like a custom recovery is very, very close. Once that happens, making this into a flashable modification will be trivial.
The very active Note II development is incredibly helpful, because our hardware and software are so similar to theirs.

I know this was something that users on the other Galaxy Note 2 threads were doing, and was wondering if at some point this will be an issue with say JB 4.2.2. I recall that Apps2SD would be an issue later on and wouldn't work, but I never got to that point. For me I am really in need of a 32GB tablet and just can't compromise even with a 64GB microSD card. I don't know why this tablet isn't supporting a 128GB microSD card, that would be awesome.

Upgrading internal storage by blending in sdcard
Just to be clear - this mod does not allow app2sd style migration of apps (in /data/app) to the sdcard.
Rather, it puts /data/media on the sdcard. A lot of apps use /data/media as their default for storage, though, so it's a helpful middle ground. Also, your apps are installed whether or not the sdcard is inserted, which is helpful.
I notice that the update includes a script called
install-recovery.sh - the same script that this method is using.
I have tested replacing a backed up copy of install-recovery and also
appending the command
run-parts /system/etc/init.d/ to the new file.
Using just a script to call run-parts or the stock install-recovery.sh works just fine.

I found a much easier way of doing this.
http://forum.xda-developers.com/showthread.php?t=2276193

hi friends & master
please help me
Is there any way to transfer games and apps to the internal storage with app2sd (moving apps & games in from system Rom to SD card(internal) no memory card)?
my system rom There is almost full
1.44 GB (148 MB free)
internal 12.6 GB (5.8 GB free)
SD card 12.5 GB (5.6 GB free)
I do not need to memory card

Mount EXT4 MicroSD Card

I've given up on reformatting the internal memory as EXT4 (my last post). However now, I want to mount an external SD card that is EXT4 (or any file format that has UNIX permissions). I can't get my device to mount the card, it says the filesystem is unsupported. Now, that's bull**** since Android has built in support for EXT. After searching threads here on XDA and Google, and even purchasing EzyMount as recommended, I can't get it to mount. I've tried BusyBox and mount commands (as root), with various errors such as "mount operation not supported on transport endpoint". I'm at my wit's end by now, trying to get some filesystem which has support for symlinks and UNIX permissions... any ideas?

kcattakcaz said:
I've given up on reformatting the internal memory as EXT4 (my last post). However now, I want to mount an external SD card that is EXT4 (or any file format that has UNIX permissions). I can't get my device to mount the card, it says the filesystem is unsupported. Now, that's bull**** since Android has built in support for EXT. After searching threads here on XDA and Google, and even purchasing EzyMount as recommended, I can't get it to mount. I've tried BusyBox and mount commands (as root), with various errors such as "mount operation not supported on transport endpoint". I'm at my wit's end by now, trying to get some filesystem which has support for symlinks and UNIX permissions... any ideas?
Click to expand...
Click to collapse
you fully rooted with custom kernel or only with rdlv etc?
First you gotta figure out how to mount this damn thing, gotta be possible.
Then you need to get this done on bootup, either in init.rc or init.d or smth.
You probably just use wrong commands? But I could be wrong, didnt try that yet but would also be interested. Having the file permissions also on SD would be nice, but it could cause trouble with mtp maybe?

zroice said:
you fully rooted with custom kernel or only with rdlv etc?
First you gotta figure out how to mount this damn thing, gotta be possible.
Then you need to get this done on bootup, either in init.rc or init.d or smth.
You probably just use wrong commands? But I could be wrong, didnt try that yet but would also be interested. Having the file permissions also on SD would be nice, but it could cause trouble with mtp maybe?
Click to expand...
Click to collapse
I am rooted, but stock ROM and kernel. MTP is for connecting to a computer? If it is, I don't need that. I have tried
mount -rw -t ext4 /dev/block/mmcblk1p1 /storage/extStorageCard
and variants switching the flags and options.

Interesting... I just typed that command in to make sure I didn't make any typos.... and my phone crashed and rebooted. I typed it again to see if it would cause another crash and it appears to have mounted the card! Whwn I type "df" at the prompt it now shows a 28.6 GB filesystem at that location, which has to be my sd card.
Why, how, I don't know. It works, it's all I can say.

Any script to move part of the internal data to SD ext in Lollipop 5.1.1?

I am looking for a script that basically covers the Link2SD functionalities. But using mounts instead of links. I actually made one for GB that worked up to KK, but now Lollipop is behaving in some weird ways regarding binding mounts. I also tried Mounts2SD (the apk) and I get the same results.
To make things a bit more clear, I'd like to be able to at least mount /sd-ext/dalvik-cache over /data/dalvik-cache, where /sd-ext is the mount point for the second partition (in ext4 format) of the external SD card. Does anyone use/know about a working script for 5.1.1?

I'm using FolderMount from the PlayStore. Didn't try the dalvik cache but for normal sdcard -> ext-sdcard its working perfectly.

Well, yes, FolderMount helps with games or any other app with large obb data. I use it indeed. But I need to move stuff from /data to the external 2nd partition because 5GB with Lollipop 5.1.1 are not really much. Especially considering that after 3.70GB one starts to get the annoying notification about low internal memory.

Yes my comment is stupid, you need a script which is doing this before any app startup because dalvik is the optimization for these.
Just an idea not sure if init.d is executed in the right time. But if your rom has init.d enabled (not emulation, real init.d) then you can put a script in /etc/init.d which does the mount job.

That's what I need. As I wrote I made that script already on GB and recovered it for KK. Just a couple of modifications and it was up and running again.
The problem is that with Lollipop Android keeps an hold of the original /data and all its subdirectories. So whatever I mount doesn't matter to it, it still keeps using the /data folders as if nothing happened. So I wondered if anyone had found a solution for it and made a new script 5.1.1 ready.

Ok, it's probably impossible to do (unless of having access to the kernel RAM disk). I've found out that the issue could be related to the separated mount namespaces. There is an option in SUperSU and I disabled it. After mounting the directory and starting ART it crashes badly, rebooting the phone (kernel included I believe).