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Is there better way to get applications on sd card. Why are we using ext2 ? We can format sd card and partition it without using pc . We can format it into native supported file system of fat. why are need to make dev when in /dev/block device exist ? we need just to modifiee mounted.conf and /etc/fstab
I think because it's easier to say then to do But if you can make it so easy i love to use youre methode! (newest way is pretty easy, flash modded JF rom and exec a script and you are done: http://forum.xda-developers.com/showthread.php?t=480582)
I would think that you could run into issues with permissions/etc if you tried to use a FAT filesystem to store applications.
About the only advantge of FAT is its ubiquity. In every other regard there is a better solution out there. Ext2 is by far the most widely supported linux filesystem that supports the full POSIX feature set.
simply put FAT32/VFAT is a horid horid filesystem, and does not support unix permissions, symlinks, etc.
EXT2 is a native linux filesystem, supports all of the above and has been time tested as stable.
That said it would be slick to get EXT3 (or 4!) support, or even reiserFS support.... journaling FTW
Well, you could just compile the kernel module, but your flash would probably survive a week with journaling... theres a reason you don't use it on flash.
Flash gets worn down by use, and journaling writes every second... So, journaling FTL.
tritron777 said:
Is there better way to get applications on sd card. Why are we using ext2 ? We can format sd card and partition it without using pc . We can format it into native supported file system of fat. why are need to make dev when in /dev/block device exist ? we need just to modifiee mounted.conf and /etc/fstab
Click to expand...
Click to collapse
the phone is linux .. EXT2 is linux .. FAT does not support proper file permissions and if you wanted to try setting something up feel free .. however .. you mention "native" supported file system and that is linux .. storage on the SD comes standard with FAT file system simply because the phone only uses it to store extra files like MP3 and JPG etc .. applications need a higher level of communication that FAT just cannot handle .. that's why Microsoft gave up on it for windows
Hi all
I have all my apps and data moved to the sdcard a while back but my phone crashed and I decided to move only the apps to the sdcard.
I'm trying remove the /system/sd/data folder on the sdcard and keeps getting that error message. How to fix it?
Thanks
This should only happen if an NFS export is mounted to a linux box of some sort, and that export has changed or otherwise become inaccessible.
any idea how to fix it?
i have this problem, i'm not able to delete the data folder beacause of that error. :/
your ext2 partition is corrupted. this happens quite a lot if data is moved to the sdcard. boot up linux and run fsck on the sdcard and that should fix it.
cool. I'll give that a try.
Thanks
I'm having this problem too. Can you provide some basic instructions for how to mount and fix under linux? I have an ubuntu vmware image I can boot to on my windows pc and a usb card reader. Will that suffice?
When you plug the card into an ubuntu box it should automatically mount it as the next available drive. You'll have to figure out what device node the card shows up as, unmount it (umount /dev/<insert device name here>), and then run a filesystem check (fsck /dev/<insert device name here>) on the unmounted card. The utility will report various problems about "inodes" which you will want to say yes to fix. Once it has run through the file system should be in a consistent state and ready for use again.
You run the risk of losing stuff written to the card (which is probably corrupt anyways) when you run the fsck so you may want to take a copy of the data first.
On a side note: I am not sure what the default mount options are listed for moving the stuff onto the sd card in the faqs but I suspect it may help prevent corruption to mount the card on android with the sync option. Though, this will definitely slow writes to the card. It would definitely be a bad idea to remove the card while your G1 is running either way.
equid0x said:
On a side note: I am not sure what the default mount options are listed for moving the stuff onto the sd card in the faqs but I suspect it may help prevent corruption to mount the card on android with the sync option. Though, this will definitely slow writes to the card. It would definitely be a bad idea to remove the card while your G1 is running either way.
Click to expand...
Click to collapse
I was thinking of using the sync option, but then I read this at http://linux.die.net/man/8/mount:
sync
All I/O to the file system should be done synchronously. In case of media with limited number of write cycles (e.g. some flash drives) "sync" may cause life-cycle shortening.
Click to expand...
Click to collapse
Busybox seems to have an fsck command built in, but I don't think all the supporting stuff is there. I'd like to have a way to fsck my ext2 partition while on the go and not near my linux box.
I know that you can't fsck without unmounting the partition and of course it would be bad to unmount the partition with apps on it while the phone is running, but I was thinking it would be nice to be able to boot into the recovery console.
I tried this and attempted to do a fsck on /dev/mmcblk0p2 with the fsck in busybox as follows:
Code:
busybox fsck -t ext2 /dev/mmcblk0p2
But the error I got was that fsck.ext2, which is the actual executable that should be used, isn't there.
What would it take to get this onto the system so that I could boot into recovery and do a quick fsck and then reboot back into phone mode?
I was thinking of using the sync option, but then I read this at http://linux.die.net/man/8/mount:
Click to expand...
Click to collapse
Where flash lifetime is concerned... I agree, this will certainly have some impact. However, the amount of wear concerned really depends on the number of write cycles the particular flash you are writing to can handle, and how good any wear leveling in the memory controller is. Modern flash memory will likely last on the order of years even with tons of writing going on. If all you are moving to the card are the apps, that data will likely be written once (or maybe a few times over the life of an app) and only re-read from that point forward. The caching will eventually commit any data in the buffer to "disk" regardless of how much is actually there. The idea is to line up all the writes so they can be done efficiently. Where ext3 is concerned, the commit interval is 5 seconds by default, I am not sure what it was in ext2 but I imagine it is similar. Ext2 is not really a flash optimized filesystem, but it is readily available on basically any linux distro, and is supported on Android. A better fs for flash drives where write cycles are an issue might be something like jffs2 or yaffs.
At any rate, sd cards are cheap. Why not just throw it away when it starts to die?
But the error I got was that fsck.ext2, which is the actual executable that should be used, isn't there.
What would it take to get this onto the system so that I could boot into recovery and do a quick fsck and then reboot back into phone mode?
Click to expand...
Click to collapse
You would have to compile an ARM6 compatible version of fsck and get it onto the recovery partition so you could run it.
just turn off your phone, pull out the sdcard, boot on a linux os and
then in console type :
fsck -p /dev/your_ext2_partition
Is there any way to clear this error message on a windows xp computer?
Maybe use pargon partion manager, but where do I go to fix it in pargon?
equid0x said:
Ext2 is not really a flash optimized filesystem, but it is readily available on basically any linux distro, and is supported on Android. A better fs for flash drives where write cycles are an issue might be something like jffs2 or yaffs.
Click to expand...
Click to collapse
Hmm... Well, we know that yaffs is supported on Android because that's what the onboard storage uses. So I wonder why the tutorial for apps-on-sdcard suggests creating an ext2 partition? Couldn't we create a yaffs partition on the sdcard and use that instead?
Maybe because yaffs isn't as commonly supported in non-Android partitioning tools (which you would have to use to set up the card initially)?
In any case, if there's no real downside to having the partition be yaffs, how can I go about formatting it as such? I don't recall seeing such an option on gParted or anything, but then again I didn't look that carefully.
So can anyone clue me into how I might add yaffs/yaffs2 support to my desktop linux box? I'd like to try using a yaffs2 partition rather than ext2 to see if I get better reliability, but I need to add support for that filesystem first. Can't seem to figure out how to do that quite yet...
You will likely need to create the partition from the terminal using something like fdisk or cfdisk which will allow you to select the proper filesystem ID. The command for creating the filesystem is mkyaffs. The fstab in android will need to be modified to enable mount of this file system at boot. You will need to install all of the yaffs support tools on a linux desktop to get access to the mkyaffs command.
Yaffs is designed to be used directly on NAND or NOR flash memory (not abstracted through the controller built into an SD card) but it may work anyways. I am not very familiar with the specifics of this particular FS. Most of these flash filesystems are designed to provide a bootable root filesystem for an embedded device.
Yaffs kernel support can be built into a custom kernel with the instructions here:
http://yaffs.net/howto-incorporate-yaffs
Its not likely you will find pre-made packages for any of this in a common distro like Ubuntu. So, you will need to know how to compile it all by hand. A good starting point for a lot of linux info is The Linux Documentation Project at:
http://www.tldp.org/
FWIW I have built homebrew linux based routers for dual ISPs, IPSEC VPN and the like using a lightly modified version of CentOS and 4GB CF cards plugged into an ATA adapter. I used EXT2 on these and they were in production use at a small 13 server farm for a couple of years before being replaced with newer equipment without any failures whatsoever.
I have also used CF cards in small 200Mhz cube PCs as basic web kiosks for extended periods of time without any failures as well.
Under normal usage patterns on a mobile device probably does not require a large amount of writes in the grand scheme of things. I'd say it is fairly likely that your card will outlive the device you are using it in regardless of the filesystem in use.
If you are seeing lots of corruption I would suspect a flakey/failing SD card or some other hardware related problem. It definitely pays to buy high quality flash media. I would also suggest not allowing the phone to constantly run dead if you know things are being written to the SD card, since random power failures during a write to flash can permanently damage the media.
Hi, I have been testing several NAND set-ups
-system to NAND and data to resized data,img
-system to resized system.img and data to resized data.img
-system to NAND and data to ext2
...
I am currently using NAND and data to ext2 partition, so all apps are installed there. After lots of reading I can not understand posts that are obsolete and posts that are not so I would appreciate if someone can explain me the basics and optimal setup for incubus superfroyo RLS14/15 roms:
I have now 4 partitions:
1) fat32,
2) 1,5G ext2 (app, app-private etc),
3) 1,5G ext2 (lost+found folder) and
4) 96M lynux-swap.
- How can I turn ext2 to ext3? do I need to do so? I have also read about ext4. Upgrading to ext3/ext4 applies to my 2) partition, to my 3) partition or to both? will I loose data stored? "there is no ext3/ext4 fs because there isn't the support on the compiled kernel. Ext3/ex4 are journal file system so are bad for limited writing device like nand or sd and thre is no good rease to use it" answered by l1qd1.
- How can I check if my lynux-swap is enabled and used by the rom?
- Do partitions 2) and 3) really need to be <1,5 G? why so?
- Can I take apk from apps folder in partition 2) in case I want to keep them for future fresh installs?
- What is lynux-swap optimal size? a 1,5G partition would be worse than 96 M? Why?
- Which tools are you using with incubus roms to manage installaion location and similar functionalities?
Another big mark I have is about deoxeding installed aps (not belonging to the ROM). Should I do it? why? how?
Pretty basic stuff I guess for experienced users & programmers, but I am new to lynux and android. Have read lots of things but it is difficult to learn by myself what would work with our Polaris and incubus ROMS and dzo/kk kernels,
Stick to ext2 man, you won't turn your old engine to 240mph on a Ford Model T.
You're not getting some major boost if the hardware dosn't use it, so I'd stick with ext2.
And you also want Super FroYo on your ext2 partition, yes? I'm here to help.
- How can I check if my lynux-swap is enabled and used by the rom?
adb shell
Code:
free
if on swap you have 0 it isn't enabled.
Code:
swapon /dev/device
to enable it or i suggest you tu use compcache.
- Do partitions 2) and 3) really need to be <1,5 G? No
- Can I take apk from apps folder in partition 2) in case I want to keep them for future fresh installs? Yes but not all apk support this
- What is lynux-swap optimal size? a 1,5G partition would be worse than 96 M? Why? Too Big = more sparse but it's a problem only for real disk so you can create a swap big as you want but it's unuseful (100 M is enaught)
i suggest you to switch to my kernels because are more updated and kk move to another device.
Yah l1q1d I love ur kernels. Eager for more !
l1q1d, I am testing your kernel as you advised me. I could apply the wifi patch without problems using your androiupdate18-09-10, as you told me some time ago they are both 2.6.25.
However I do not manage to turn linux-swap on: that's what I do: I install ubuntu, I use G-Parted to create partitions on the sd card. When I do so, the third partition is always shown as linux-swap in G-Parted but when I test adb shell -> parted -> print, it always shows as ext2. I can not dismount and can not swap on it.
The other way round, if I deleted all partitions with G-Parted and create the partitions with mkpartsfs or if I use mkfs to change the third partition from ext2 to linux-swap, then sometimes I can swap on it (directly on adb shell or with G-Parted) but when I unplug the device will tell me the card is empty and will not be able to mount it, access it from ubuntu or from the device. If I reboot then, the system will hang until I install both data and sysetm to nand. This happens no matter if I activate or not from the polaris or even if I switch on or off usb mode. The card at that point is useless. I guess the partition table or some other basic file is messed.
Could you please explain a little more how can I come with a 13.5G fat32 partition, a 2,4 ext2 partiions and a 0,1 lynux swap swapped on partition??
I really need to test this set up, since with the standard set-up (system to nand, fat32 for files and ext2 for installed apps I can not install all apps I use since performance drops significantly).
regards
well, ... dumb me, maybe with compcache you are referring to launch a script?
where do I get this compcache.sh? how do I launch it? from adb? from the terminal? from the sd card?...
Ok. So lots of talk about ext for apps2sd and how it's being mounted as ext2 even if you formatted to ext4 etc.
Also talk about how journalling hurts performance and such. We'll tackle all those points here.
1. Howto fix the mounting of your ext partition in the meantime till your mod updates their software.
A. Pre-requisites
You must have already partitioned your sd card with an ext4 fs for apps2sd. You can do this in recovery or some other app.
You should also get the program file expert. It's awesome. But any filemanager that has root ability will work. You can do all this in terminal too so whatever floats your boat. I'll use file expert below.
B. Remount your system fs as read/write (not sure if it's actually needed since /system is mounted rw by most mods already... but it can't hurt). You can do this in file expert by hitting menu and selecting More, then the top option labeled "Mount", select read write. It should say success.
You can also do this in terminal but like i said above, i dont think this is absolutely needed but i always assumed it was so never tried this not doing it.
C. go back down directories using the back key till you hit /. Then goto /system/etc/init.d/
D. select S05mountsd (the S0# isn't important here so if yours is different dont worry). Once selected, hit menu and select file operations. Select permissions and change permissions to read/write all.
E. Open the file with a text editor of choice. Scroll down the file to the part that has the command with -t auto in it. It should be pretty obvious, and it's near the end.
Change -t auto to -t ext4. It doesn't matter if your fs is actually ext2 or ext3, mounting as ext4 is always better. The ext4 block allocator and general code is more efficient even if you dont use ext4 features.
You may also want to add an option to the options list data=writeback. This disables journal caching of actual data and only caches metadata. This is really integral to performance on such a slow medium like sd cards and we'll discuss that later.
Save your file and exit.
F. Reboot your phone. You should now have your sd-ext mounted as ext4.
2. data=writeback and why?
there are multiple modes of journalling available to ext4. The default is ordered. This means that there is a specific order that information is written to the fs to ensure that nothing is lost that is said to be written. This means metadata about the fs and file data is both cached in the journal. Safe but slow.
data=writeback still allows crash protection but means you may lose actual newly written data. Your fs wont be corrupt, but your file may not have gotten those last updates you were writing and had not synced yet. It's a pretty decent compromise.
There are other forms that offer better performance but basically remove journal integrity and we're not concerned with those.
There are also options that determine the interval of journal syncing and you can find that information on ext4 man pages.
Why do we care so much about performance here? because sd flash is slow and finite. A journal file is like swap in that it is a static file that's contents get written to anytime you write to your fs. On a normal hdd, it's not noticeable really but on a class 6 SD card, you are going to notice having to write everything twice to your sd card. So we choose writeback mode to remove that double writing and only cache fs metadata updates so that the integrity of the filesystem isn't hurt, and only that particular file that we crashed prior to syncing gets effected. 99% of the time this is fine and perfectly safe and way better than nothing.
3. So if journalling can hurt performance by using up write bandwidth to a medium we are writing other stuff on, wouldn't swap be bad too?
Yes. Swap should only be put on sd cards if you absolutely need it or your phone wont work. Aside from stressing the card, the bandwidth to read/write is extremely small for something you basically have to be interactive with and move to and from ram. Additionally android complicates matters by managing memory at a higher level than the kernel and this means that swap is ignored as a portion of memory. So while technically userspace apps deal with swap transparently, the low memory manager of android will operate as if you didn't have swap...which defeats the purpose.
Use swap as a last choice.
Also, the ability to make swap partitions and swap files is a common issue in linux-land. It's best to use a partition as this removes fs overhead but it becomes even more of a concern when you put it on an ext4 fs with journalling active. With default settings, a swap file will be considered just another file and the journal will cache the data and metadata updates (very bad for performance). if you use swap on an ext4 fs that's actually mounted as ext4 you _NEED_ to make the data option writeback. You will be very disappointed if you dont.
4. Other important notes:
If you use any ext4 specific options like extents, you will no longer be able to read the files written by recovery programs that have not been updated to mount fs's as ext4. Also, just enabling extents doesn't convert data on the fs to use them. You have to write the files while the option is enabled to see their benefit. This is more easily done by putting the card in an actual linux computer and mounting with the correct options and copying the data from the filesystem and then back again ....not for the novice. Though any new files written will automatically have extents even if you dont redo all current data. So best to bother with that after a fresh install prior to restoring apps.
You may also be thinking... Why do i even need a fat fs, i can make the whole thing ext4 and it will be awesome! You would be right, it would be awesome. But it's not so easy. A couple things have to be done in order to make everything written world rewritable and accessible on such a partition. you would have to setgid to a group like "sdcard" to a directory in this new fs and give it rwx group permissions and then have all users current and future become part of that group and mount bind the directory to /sdcard. Needless to say, recovery apps would have to also be updated. Then you could make your main sd partition any fs your kernel supports.
Nice post, cm7 and diet gb I build already have -t ext3 set, do you think ext4 would make much difference?
ext4 has a better block allocator and other features both backwards compatible and ext4 specific. There's really no reason to not mount ext2/3 and 4 as ext4
Thanks for the answer, This is also in the kernel I compile,
CONFIG_EXT4_FS=y
CONFIG_EXT4_USE_FOR_EXT23=y
CONFIG_EXT4_FS_XATTR=y
Yes, i began my work on the kernel tonight and noticed that in the latest kernels at least that ext4 is being masqueraded as ext2 and as i thought early on as might be the case, that the reporting of the partition as being mounted as ext2 is a bug that has been squashed in the newest vanilla kernels.
This is still an issue, but not a serious one. FS repair tools and such may bug out when trying to found out what fs they're dealing with as the kernel reports the wrong ext version but the functionality of the fs is not affected ( you still get journalling and all that jazz).
So this is less of a performance issue (cept the adding of data=writeback) and more of an issue with other programs needing to see the correct fs.
Ur Diet 09.05 still did not see ext4 partition by Titanium.
carz12 said:
Thanks for the answer, This is also in the kernel I compile,
CONFIG_EXT4_FS=y
CONFIG_EXT4_USE_FOR_EXT23=y
CONFIG_EXT4_FS_XATTR=y
Click to expand...
Click to collapse
Sent from my Gingerbread on Sapphire using XDA Premium App
If the kernel you're using is one of the newer kernels (probably anything after 2.6.32...but you should be using something much newer) then it likely doesn't even have ext2 or ext3 compiled in. It's all just ext4 like it should be. The issue you still may have however is that the kernel reports the lower revision extfs because ext4's driver accepts the ext4 fs but the kernel is checking for ext2....
Basically, we are asking if this is an ext2fs. The ext4fs driver answers cuz it's all there is and it's masquerading as ext2 and ext3 and ext4. So it looks and sees ext4 and says, hey, i can read this and returns YES. Now the answer yes was to the question of ext2, so that's what gets reported everywhere, but internally, ext4 knows it's got an ext4 fs. mount options that normally would error out with -t ext2 are accepted because the fs driver isn't really ext2 and it knows the fs isn't either so the mount options pass.
This is a kernel bug in an aesthetic and practical sense. Functionally it's all working as intended but other apps and users will get confused as to what exactly is the filesystem, ext2, ext3 or ext4. It can't know without probing the fs itself. Which is stupid for many applications.
Supposedly the latest kernels have a patch to fix this to correctly report the correct fs revision of ext. Though perhaps that hasn't been pushed to linus's branch yet.
In any case, you still should be modifying the mount options to use data=writeback so you're not clogging up the little SD bandwidth you have with data caching in the journal. You really only need fs metadata caching so you dont bork the entire partition on a crash. data=writeback does that, but default is data=ordered.
thank you for such a good post!
Let me start with: I know that there have been many posts on this, but before you get mad, I was unable to find an answer to what I specifically want to do.
For reference: I am a software developer and sysadmin with a decent amount of Linux experience, but not a lot of android specific experience.
Now that the introduction is out of the way:
What I would like to do is completely remove the "USERDATA" partition (the "Internal SD card"), grow the "SYSTEM" partition to fill that space, and then mount my SD Card (external) as the SD Card that the system sees.
I'm currently on Cyanogenmod 10.1 but want to upgrade to 11 soon.
The reason I want to do this is because:
I have all if my apps that I can set to install to SD Card
Both "internal" partitions are full (only about 200MB is available for pictures/etc. and I can no longer update apps)
Camera (and pretty much everything else as well) stores to the Internal SD card by default
If the system partition was 1.1+1.4=2.5GB and all of my apps were "installed" to a real SD card, it would be a lot more comfortable.
So, here's what I am thinking *might* work (maybe not in the right order, though?):
Point the fstab entry for the internal SD card to the external SD card
I have the PIT file. I will delete the "USERDATA " and grow "SYSTEM" to fill the space
When I write it out in steps, it seems pretty simple...
My concerns:
Will a ROM update (to CM11) re-partition back to the old way (and, in the process, break a bunch of stuff)?
I don't ever plan to go back to stock android or change to another ROM (other than upgrades).
Thanks for reading this long post and for any insight you may be able to provide.
--mobrien118
It's a wonderful idea if it works.
Sent from my SAMSUNG-SGH-T769 using xda app-developers app
Modifying partitions is a bit dangerous.
But I have to ask you why do you need another GB of /system storage?
There was a line you can put in the build.prop that flips your ext. SD with the internal one on cm10 I believe.
This'd interest me if I could get rid of usbdisk and sdcard0 merged.
It would need the phone to be repartitioned though, causing issues with the backups and ROMs.
You may even have to compile cm from source.
Its a lot of trouble
Sent from my SAMSUNG-SGH-T769 using Tapatalk
I just did so on S4 Mini with cm-11 Android 4.4.
First I was thinking of using symlinks and/or bind mounts to redirect to the the external sdcard, but that's a bit of a hassle because
1) Since 4.2: both emulated and external storage is mounted with a fuse layer on top not supporting symlinks
2) Since 4.4: no more global write access on external storage
So moving data was the simplest solution. Besides providing (much) more space my sdcard is also around 20% faster in sequential writes: 8.5 MB/s internal vs 10.5 MB/s external. Is it really 2014?
I haven't yet decided what to do with the original data partition, so for the moment I left it unused. Hence I haven't touched the internal partition table.
Quick summary
partition sdcard (gdisk)
I recommend using GPT, this lets you work with partition names rather than numbers. For the sake of still having an "official" external sdcard I made two partitions. Keep in mind that it's usually the first partition which gets automatically mounted as external sdcard. So I made the 2nd partition the new home for data. This partition however has to be manually specified in the ramdisks fstab which involves flashing the boot partition.
format the new partitions (mkfs.ext4)
copy the original /data directory tree to the new data partition
extract initrd from boot.img (abootimg)
extract files from initrd (gunzip & cpio)
replace the /data entry in fstab pointing at your new data partition
re-pack initrd and boot.img (gzip, cpio & abootimg)
flash boot.img onto the boot partition (dd)
If you use recovery, you also have to edit it's fstab (analog to boot.img mentioned above)
done
Alternatively has anyone tried an init.d script? I see those scripts get executed before the mounting of data & sdcard
Meanwhile the original userdata partition got replaced by 3 new partitions: system2, cache2 & userdata2 which are now used for a dual boot ROM.
I've only changed GPT, not PIT. ROMs and Recovery don't use PIT, so as long as Heimdall/Odin isn't involved it should not cause any issues.
Hey guys,
So after read all that, I am also vry interested in what the OP has suggested. I get that the pit doesn't need to be affected, but as the OP asked, when flashing a new rom or updating an existing, would the partition be reformatted back to the way android handles it, ie; back to the system and data seperate and the sdcard not being used as the internal partition?
I am no developer and only have minimal knowledge in linux and android programing, but I am a quick study and any guide to help me sort this would be greatly appreciated.
Also I am about to get a second S4 mini specifcally for doing things like this so if I brick I don't care?
My next question is could it be possible to code the PIT file to do this for you so that you can just flash that through odin, but again would flashing roms affect this.
Cheers,
Sora.
aguaz said:
I just did so on S4 Mini with cm-11 Android 4.4.
First I was thinking of using symlinks and/or bind mounts to redirect to the the external sdcard, but that's a bit of a hassle because
1) Since 4.2: both emulated and external storage is mounted with a fuse layer on top not supporting symlinks
2) Since 4.4: no more global write access on external storage
So moving data was the simplest solution. Besides providing (much) more space my sdcard is also around 20% faster in sequential writes: 8.5 MB/s internal vs 10.5 MB/s external. Is it really 2014?
I haven't yet decided what to do with the original data partition, so for the moment I left it unused. Hence I haven't touched the internal partition table.
Quick summary
partition sdcard (gdisk)
I recommend using GPT, this lets you work with partition names rather than numbers. For the sake of still having an "official" external sdcard I made two partitions. Keep in mind that it's usually the first partition which gets automatically mounted as external sdcard. So I made the 2nd partition the new home for data. This partition however has to be manually specified in the ramdisks fstab which involves flashing the boot partition.
format the new partitions (mkfs.ext4)
copy the original /data directory tree to the new data partition
extract initrd from boot.img (abootimg)
extract files from initrd (gunzip & cpio)
replace the /data entry in fstab pointing at your new data partition
re-pack initrd and boot.img (gzip, cpio & abootimg)
flash boot.img onto the boot partition (dd)
If you use recovery, you also have to edit it's fstab (analog to boot.img mentioned above)
done
Alternatively has anyone tried an init.d script? I see those scripts get executed before the mounting of data & sdcard
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I just managed to replace my internal sd with the external sd following your ruff guide. thank you very much! At first I struggled a bit getting it to work, because I had encrypted my data partition before -.- this seems to change something in the fstab / mounting / boot-up process, I couldn't get my S4 mini to boot with just changing the fstab.qcom in boot.img. With my recovery (TWRP) it worked from the start editing recovery.img's fstab.twrp /data mount point.
After decrypting(formatting) /data and re-editing fstab.qcom in boot.img it finally works I'm so happy! Enjoying a lot of space on my sdcard now!
usefull threads / information I learnt from:
Partition structure of S4 Mini
Encryption of ExtSD & some fstab information
Editing initrd
abootimg ReadMe
(Links last tried 28.05.2015)