Database Develop

[HACK] mount sdcard as ext4

These patches add ext4 support for your sdcard (in the Nexus S - the internal card.) There are a number of reasons you might want to do this - performance (ext4 is faster, plus mounting ext4 is basically instantaneous, which is very nice on reboots...no more checking sdcard), it's more efficient, you get a bunch of file system security features (if you care...)
You should not apply them if you don't really know what you are doing. The patches are resonably benign. Converting your sdcard partition to ext4 is NOT NOT NOT benign and you can really hose yourself doing it.
I'm not going into great depth with these instructions. If you don't understand them, play around with building cyanogen, installing it, etc until they are crystal clear.
To swap your sdcard to ext4:
* Apply the patches and rebuild cyanogen. Rebuild it. They will change your recovery image and vold.
* Install vold and flash (and/or boot) the recovery image.
* Boot into recovery, mount your sdcard and back it up to your computer (i.e., not nandroid, copy the files.) Nandroid would be a good idea too.
* Format your media partition to ext4 (the one that is vfat, by-name is media, mine is partition 3) mkfs.ext4 can be found by googling, or you can use make_ext4fs from /system/bin. I used mkfs.ext4.
* You should be able to manually mount that.
* Push your files back.
* sync and reboot.
Et Voila, you should have an ext4 sdcard partition.
THIS IS VERY DANGEROUS.
YOU CAN REALLY HOSE YOURSELF DOING IT.
Here are the patches:
http://review.cyanogenmod.com/#change,1705
This one adds ext4 support to vold, thus allowing gingerbread to mount ext4 partitions for the sdcard (which on the Nexus S, is the 'media' partition.)
and:
http://review.cyanogenmod.com/#change,1716
This is a change to recovery, making it seamlessly mount ext4 partitions for /sdcard.
Code:
# mount
/dev/block/platform/s3c-sdhci.0/by-name/system on /system type ext4 (ro,noatime,barrier=1,data=ordered,noauto_da_alloc)
/dev/block/platform/s3c-sdhci.0/by-name/userdata on /data type ext4 (rw,nosuid,nodev,noatime,barrier=0,data=ordered)
[b]/dev/block/vold/179:3 on /mnt/sdcard type ext4 (rw,nosuid,nodev,noexec,noatime,barrier=1,data=ordered,noauto_da_alloc)[/b]
/dev/block/vold/179:3 on /mnt/secure/asec type ext4 (rw,nosuid,nodev,noexec,noatime,barrier=1,data=ordered,noauto_da_alloc)
tmpfs on /mnt/sdcard/.android_secure type tmpfs (ro,relatime,size=0k,mode=000)

....and if you turn on USB Storage, the sdcard shows up as an ext4 disk...
As expected, but this is going to be one for the Linux geeks.
Wow, it is VERY nice to have that sdcard mount instantly on boot. VERY nice.

oh the read/write speeds

If anyone is interested in playing with this, I submitted the change to cyanogen:
http://review.cyanogenmod.com/#change,1705
The tricky bit is getting the filesystem created. You can use:
/system/bin/make_ext4fs.
That leaves me with a recovery which will not currently mount sdcard as ext4 unless I fiddle with fstab and mount it myself. On to look at that.

...and, here's a patch to the recovery which will let it mount /sdcard as either ext4 or vfat, making this change reasonably seamless.
http://review.cyanogenmod.com/#change,1716

i would love to see a Quadrant or a benchmark after this

this is and awesome hack to use with App 2 SD
it'll be lag less
the only annoyance, is that if you want to MOUNT USB on a Windows PC, then you'll need a software to read EXT4
for anyone interested this will be handy
http://www.ext2fsd.com/?page_id=16
i'll definitely be doing this MOD, as i'll be running anything i can from the Internal SD

So this will only work on CM7?

Please some of the genius here may post a step-by-step tutorial or howto for this one? It will be very apreciated.

No, it will work with any build, but you need to rebuild vold in order to get it to mount. The easiest way to get them outside of the CM tree would be to build cm and then copy the vold out and use that. It should work with any ROM.
The latest versions - which are in CM's gerrit - include modifications to the sdcard utility to use fuse to mount the filesystem using FAT semantics (i.e. - bypass security). Frankly, this is a waste. It slows everything down, noticeably, and app problems are few and easily fixed if you know how to fire off a chmod.
I haven't provided step by step instructions since it can seriously hose your phone if you don't know what you are doing.

DebauchedSloth said:
No, it will work with any build, but you need to rebuild vold in order to get it to mount. The easiest way to get them outside of the CM tree would be to build cm and then copy the vold out and use that. It should work with any ROM.
The latest versions - which are in CM's gerrit - include modifications to the sdcard utility to use fuse to mount the filesystem using FAT semantics (i.e. - bypass security). Frankly, this is a waste. It slows everything down, noticeably, and app problems are few and easily fixed if you know how to fire off a chmod.
I haven't provided step by step instructions since it can seriously hose your phone if you don't know what you are doing.
Click to expand...
Click to collapse
Wait so it's a waste? It isn't worth using ?

Anderdroid said:
Wait so it's a waste? It isn't worth using ?
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Click to collapse
If done right this would increase the read/write speeds. For example, your boot up time would be much faster and ext4 is more effecient. So it's not a waste but it has to be done correctly otherwise is could do more damage than good

Using the version I posted to CM gerrit, which bounces the file system through fuse and mimics FAT security, is still better than FAT (IMO), but it's not nearly as fast as just mounting the filesystem as Ext4 - though it is more compatible.
I've been running mine mounted as straight ext4 for a couple of weeks. Probably the single best mod I've made to any of my phones. There are occasional app bits that I need to fix manually (such Dropbox resetting file ownership), but it's worth it for the quicker boot up and faster overall operation.

Here you find the ROM CyanogenMod 7 compiled for Nexus One with ext4 sdcard mount support:
- https://github.com/diegostamigni/nexus/tree/master/one

Is the only reason to pipe it through fuse to get it to mount on m$? If so I'm not going to bother - I only use linux almost exclusively these days

diego.stamigni said:
Here you find the ROM CyanogenMod 7 compiled for Nexus One with ext4 sdcard mount support:
- https://github.com/diegostamigni/nexus/tree/master/one
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Click to collapse
No version for Nexus S?

Looking forward to this develpoing, as the ext4 conversion (done via modaco rom beta2 in recoverymode) made a HUGE difference to the galaxy tab i have (halved the loading times of everything). ^^
Unfortunately im far to noob to help out though ...will be keeping a keen eye on it all and learning

Forgive my ignorance, but why don't phones come like this?

NicholasQ said:
Forgive my ignorance, but why don't phones come like this?
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window$ more then likely.
window$ can't even see Linux file systems without special drivers installed.
if i mess this up would it brick my phone? i'm really wanting to try this but i don't want to turn my Nexus S into a paperweight

so if we did this, would the windows computer be able to read the mounted sd card? is there any other things that would be needed after this mod? or just format to ext4 and be done with it?

Alternate Webtop partition

I was hoping to be able to figure all of this out on my own (so that I could impress everybody with my brilliance, of course! ), but I've hit a brick wall, so I figured I would see whether anybody had any suggestions.
The short version: I'd like to be able to create an alternate and larger /osh partition that we can run Ubuntu off of so that we can install software more freely as well as not worry about any future software updates that might conflict with the partition contents.
My thought was that it should be possible to have an alternate partition to /osh that's used to run from (whether it's mounted on /osh or not is largely irrelevant).
However, the problem I'm hitting up against is a matter of timing. The best entry point I've found to modify behaviour is /system/bin/mountosh when it's called by /init.rc, especially since it's responsible for most of the webtop setup. The catch is that by the time mountosh is called, the only partitions mounted are through p16, meaning that internal storage (p18) isn't available and the SD card (mmcblk1) isn't available either, meaning that there's no way to use either (a loopback file on the former, a partitioned SD card for the latter). I suppose it would theoretically be possible to create a loopback file on p16 (data), but that's only 2 GB and would conflict with other uses.
Does anybody know how to force internal storage and/or the SD card to be mounted earlier? Or is this going to require hacking a kernel (and bootloader and...) that we don't have the source code to yet? If I can get past this piece, then I'll be able to help other users get a webtop that would be in much better shape (especially since this would let us start using apt without having to worry so much about space issues). Thanks!

I am not sure off hand at the moment, but you might have a look at /etc/fstab and see if you can have the sdcard mounted earlier there. While having it mounted earlier may have some unexpected side effects; I presume the driver for the sd card reader is compiled into the kernel, so I don't see a reason it can't be mounted earlier.
But, not having an atrix anymore I can't test this outright.

Fenny said:
I am not sure off hand at the moment, but you might have a look at /etc/fstab and see if you can have the sdcard mounted earlier there. While having it mounted earlier may have some unexpected side effects; I presume the driver for the sd card reader is compiled into the kernel, so I don't see a reason it can't be mounted earlier.
But, not having an atrix anymore I can't test this outright.
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/etc/fstab is pretty meaningless, unfortunately. Most of the mounting is performed within /init.rc, and I see no entries for the external storage there. As it stands, the entry for the internal storage is more in the format of "on X, do Y" rather than the more traditional procedural format, so I'm not sure how much control I can have over that.
Also, second thoughts tell me that putting a filesystem file in /mnt/sdcard would be stupid, because it would cause all kinds of issues when attempting to USB mount the partitions from a computer.

I think the best way to attack this would be to pivot to another filesystem structure on the external sdcard. I'll take a look at init.rc later today and see what can be done.

agentdr8 said:
I think the best way to attack this would be to pivot to another filesystem structure on the external sdcard. I'll take a look at init.rc later today and see what can be done.
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So you'd think. And that's what I did. I have a nice 2 GB ext3 partition on my SD card with the contents from the /osh partition (p13) rsync'ed over. But, only the mmcblk0 partitions are available when mountosh runs (up through p16), with no mmcblk1 partitions. Naturally, /dev/block/vold is empty as well.
I might need to poke some contacts to see if it's possible to detect mmcblk1 earlier, but in the meantime, I might just create a filesystem file in /data (p16). Hell, /data is almost 2 GB large, and I'm only using a little over 500 MB in it, so there's plenty of free space there. Why did they make it so large? Do people really download that much crap to their phone?

Grr...
So, even creating a file in /data and mounting that via loopback doesn't work, even if it's mounted on top of the existing /osh partition. I'm guessing that they have some level of verification.... So yeah. Something else is missing here.

I had two sucessful ways of overcoming this. The first way was to move /usr onto /data, and to symlink it back. But, I wanted a way of not modifying /osh, so I ended up creating a init.d script to bind a copy of /osh over /osh. I don't have access to a dock or HDMI monitor at the moment, so I can't confirm if the webtop launches with either of these methods, but full functionality worked in the command line.

shawnbuck said:
I had two sucessful ways of overcoming this. The first way was to move /usr onto /data, and to symlink it back. But, I wanted a way of not modifying /osh, so I ended up creating a init.d script to bind a copy of /osh over /osh. I don't have access to a dock or HDMI monitor at the moment, so I can't confirm if the webtop launches with either of these methods, but full functionality worked in the command line.
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Click to collapse
Yeah, that's the thing. Everything worked on the command line, but X itself refused to start, even after I completely disabled TOMOYO (even when running /etc/init.d/startX.sh by hand).
I might decide to poke at it another time, but I'll at least wait for the SBF situation to sort itself out first.

[Q] Using a SD-Ext Partition

I'm wondering if it's possible to create an ext3/4 partition on the SD-card and use it for files over 4gb. The main reason I want this is to play with Backtrack 5 for the ARM architecture. I'm guessing it should be as simple as partitioning my SD-card w/ a Fat32 partition as the first partition and then ext3/4 as my second and then adding a mount option into the fstab file. Just wanted to run it by anyone else that has already done it, or knows a better way.
PS. In case anyone else is interested, here's a thread with partial instructions on install Backtrack (if you're familiar with Linux, figuring out the rest shouldn't be difficult): http://forum.xda-developers.com/showthread.php?t=1074723&highlight=backtrack
Edit: Just found this: http://denniskuntz.com/blog/2011/05/11/backtrack-5-on-the-nook-color/ So, it seems it's possible. But, still have the question of can you have both a FAT32 and a ext2/3/4 partition on there and keep your nook functional as normal, but have a separate partition to run BT5 off of?

[Q/Dev suggestion] Space for another big ROM slot in internal storage?

Taken from CM12 thread as this started to become off-topic. The issue I'm trying to address is how to stuff a huge Lollipop ROM directly into internal storage, without creating a virtual slot, to increase system performance and have overall cleaner solution. Original inspiration: @Mentor.37's custom Safestrap for unused partitions, which has way too small /data for me unfortunately. (explanation)
sd_shadow said:
Septfox said:
This in mind, is there any way to repartition the internal (stock) storage to decrease the size of /cache/ and create a larger /data/ partition, or is it not possible without modifying the bootloader?
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Code for mounting the unused preinstall and webtop partitions to SD storage http://forum.xda-developers.com/showthread.php?p=59253593
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Click to collapse
This allows you to mount the partitions either as a new storage or to a specific directory only, in other words it does not merge the storages, just adds a mount point next to (or possibly if modified a bit on the top of) other storage. While this may be useful for taking some inherent load off /storage/sdcard0/ (i.e. mounting /dev/block/webtop to /storage/sdcard0/Downloads) for people not swapping their sdcards, it doesn't help in Septfox's intention of enlarging /data/.
I face the same problem as Septfox: I'd love to use the storage intended for running system for it, not virtually mounted storages created in the storage intended for storing media and support data. However, the outline of the storage is intended for way older and less robust system so even the /system/ is not quite enough (667 MB, which tightly fits CM12 with a small GApps package) and /data/ is also not enough for heavier use (3.22 GB). Therefore I would like to merge it with currently unused partitions: maybe join preinstall to system and webtop to data, making both big enough.
One alternative would be to mount the 1.4 GB webtop as /data/app, which currently makes about 2/5 of occupied space of my /data. Is this possible? At which point of system startup is the script in /system/etc/init.d executed (is it done by Safestrap or the ROM itself?), and at which point might the system first need to access /data/app that contains the APKs of user-installed apps? All the really needed stuff (compiled executables) is in the /data/dalvik-cache, right? Here I'm on a really thin ice, don't know much about Android's architecture, so sorry if this is a major bullsh*t - just throwing my idea in Technically what I'm talking about is such modification of the script:
Code:
#!/system/bin/sh
mount -o rw,remount /data # Not too sure about this
# - depending on whether /data is already rw or not.
# For that I would need to know when is the script
# executed. I'm almost sure this is not necessary
# though. In original script this was done to allow
# writing into /storage/.
mkdir /data/app
#mount -o ro,remount / - unnecessary, see above
#mount -t ext3 /dev/block/preinstall /storage/preinstall
# I don't see any use for small preinstall partition.
mount -t ext4 /dev/block/webtop /data/app
chmod 777 /data/app # not sure about this either,
# probably should be 771
Clean version:
Code:
#!/system/bin/sh
mount -o rw,remount /data # Unnecessary?
mkdir /data/app
mount -t ext4 /dev/block/webtop /data/app
chmod 777 /data/app # Possibly 771 instead.
Is that possible to run, or will it bootloop, what do you think?
Even better IMO would be to delete preinstall and webtop and shrink the Stock data down to maybe 200 MB so the original Stock system is still present, preventing the phone from bricking and accommodating Safestrap. The remaining space could be divided between Safe system (say 800 MB) and Safe data (over 4 GB). Are we able to do this somehow, maybe by customizing Safestrap a bit more? Or are partitions in /dev/block locked by bootloader? Also are all these and Internal storage located on the same physical chip, or are there two separate memories in the D4? Attached proposal of repartitioned layout Sizes taken from here and here.
Developers and experienced users, I would love to hear your opinion, mainly on whether repartitioning internal storage or at least mounting webtop to /data/app could work on D4. Thanks!
Addition to the original post:
I have a spare D4 with shattered screen and not working SIM slot that I bought for spare parts. Apart from GSM (or telephony altogether? I didn't try, as only option would be emergency call which I don't want to abuse, and we don't have CDMA networks here) it works fine though. I can try meddling with formatting/partitioning - it won't be too big deal if it gets bricked beyond possibility of SBF restore.

Replies so far, taken from the original CM12 thread:
sd_shadow said:
I don't think repartitioning is possible without high risk of hard bricking the device, and yes the locked bootloader does limit what can be done.
This is quite off topic, and you should start a new thread if you are going to continue.
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Click to collapse
Good call, started new thread
lucize said:
tried to change the type of preinstall partition and the device would boot into fastboot: (invalid cg hab (cg: ebr, status: 0x0056)
so a recovery is needed, I'll try a resize if I can compile the tools in safestrap. but I think it would not work
later edit: used fdisk to resize in safestrap and it broke again so it can't be done
Click to expand...
Click to collapse
Thanks for trying! What do you mean by changing type?
As I added here in the first post, I have a spare shattered but mostly working D4 I wouldn't be too sad to see bricked - I can try out more dangerous stuff if you point me in the right direction. I'd like to help testing different approaches to repartitioning if you have some potentially harmful ideas that you wouldn't try on your own phone.
Curious question aside: where is bootloader (and fastboot) stored? Is it sitting on some other small partition? Can we mount it to be read, or even to write there? What/where is that protection that keeps us from unlocking the bootloader?
Also, concerning mounting the free partitions to other system partitions: do you think it's possible to mount them as a folder in /data (whichever we use)? Does it matter what filesystem the partitions use? What part of boot-up runs the /system/etc/init.d/ scripts? Do you think attached proposals 2 or 3 are feasible? It would still have the stock system untouched for an emergency use and Safestrap storage, but its data would be shared with the safe system, with webtop mounted as /data/app or /data/data (1.4 GB should suffice I hope) which would leave us with nice 3.2 GB for the rest. Of course, preinstall's 600 MB for /system is hardly enough for CM12 with Pico version of PA GApps so the rest of used Google apps would inflate /data a bit - but still this is probably the best option we have now.

Actually, I find the stock /system/ to be adequate. Yea, it's a tight fit, but CM12+PA Micro Gapps slots in with 30-someodd megabytes to spare, and there shouldn't be any real need for additional space on top of that. Though, I suppose there could be trouble if CM starts including larger apps.
Init.d is done by the ROM itself, and has to be enabled at build time; CM12 actually has it shut off for whatever reason (Slimkat did as well, I would imagine CM11 also did). There's an app called "Universal Init.d" in the Store, but by the time it can get around to executing the scripts, it's obviously way too late to be screwing with vital partitions : \
Worth pointing out that Safestrap appears to have proper ADB access, you might be able to do something with partitions thataway. I don't know enough about partitions and mounting in Linux to take a jab at it. Woop, looks like that's already a no-go. Maybe the bootloader does a check or three to make sure the partitions are all in order, and throws a critical error if not.
If absolutely all else fails, there's still symlinking large apps into the newly-accessible partitions that can be done, either manually or with Link2SD/similar apps. It's a bit of a hassle, but an option nonetheless.

Well, stock /system is fine but I want to keep it untouched - mainly because I don't want to install CM12 as an update over stock JB, and also to keep myself from SBFing (at least in the long run) because of trivial issues. When this option is off the plate, the remaining partitions don't seem to offer enough space to run CM11 in a non-virtual slot (as Mentor.37 offers with his modified Safestrap with a "Safe" slot with 600M system and 1.4G for data).
Symlinking is an ugly solution - used it for a while, never liked it, mainly because symlinks broke once SD got unmounted or mounted as Mass Storage, with problems remounting afterwards.
Since we can modify the system freely, I'm sure that if necessary, we could make a neater solution than using an app to create symlinks after boot. Question how early in the boot process can we add some scripts (by flashing some zipped patch over the ROM) goes to more knowledgeable devs though...

first time I just used t option in fdisk to change partition type to whatever without changing size, the second time I resized some of them and every time after 1st reboot the M logo would appear for 1 second and from now on it would go straight into fastboot without M logo, so it seems that something in bootloader is verifying the layout or something and if is not good it would stop.
I don't think that it's possible to brick it for good, use rsd to recover
Regards

Thanks to @lucize for his trying, sadly it seems we can't repartition at all
@Mentor.37, is there a source to your customized SS 3.75 available? I'd like to try and mess around with it to put the Proposal 3 from my second post's attachment to work.
Could mounting and symlinking be done from Safestrap, or does the ROM do it itself? I have ideas of various cross-linking of folders on the partitions to kind of emulate repartitioning - but I'd have to try if it works and it would need to be done either before the system boot or shortly in the process. See attachment - that's a first draft I presume for this that the user keeps stock system only for keeping the phone bootable no matter what happens in other than stock slots, so stock data would be utilized only for root and safestrap, leaving most of its 3.2 GB free.

LuH said:
Thanks to @lucize for his trying, sadly it seems we can't repartition at all
@Mentor.37, is there a source to your customized SS 3.75 available? I'd like to try and mess around with it to put the Proposal 3 from my second post's attachment to work.
Could mounting and symlinking be done from Safestrap, or does the ROM do it itself? I have ideas of various cross-linking of folders on the partitions to kind of emulate repartitioning - but I'd have to try if it works and it would need to be done either before the system boot or shortly in the process. See attachment - that's a first draft I presume for this that the user keeps stock system only for keeping the phone bootable no matter what happens in other than stock slots, so stock data would be utilized only for root and safestrap, leaving most of its 3.2 GB free.
Click to expand...
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I believe that it's impossible because symlinking "works" after kernel is loaded and safetrap take place (is loaded) before a kernel is loaded....

If I'm not mistaken, symbolic linking is a filesystem thing, something like a shortcut only more complex (after all, it's completely transparent to anything accessing it). ADB probably has commands to make links, terminal emulators in Android definitely can. I think the problem you face is making sure the mountpoint, path, etc are exactly the same both in SS and Android.
Probably better to just do both the mounting and symlinking under Android, so you can be 100% sure that everything matches. We already know /cache/ is unused most of the time under LP, and can (probably) even be unmounted while booted if needbe; why not experiment with it, rather than going straight for the other more important partitions, until you're sure what you're thinking will work?
Edit: Wikipedia has a big ol' writeup on symlinks under various systems, looks like a fun read.

rblanca said:
I believe that it's impossible because symlinking "works" after kernel is loaded and safetrap take place (is loaded) before a kernel is loaded....
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I guess then this could be implemented in some early booting stage of the system by some custom .zip being patched over, kind of the way Mentor.37's ramdisks are. Unfortunately I don't have nearly enough knowledge to do it.
What I hope could be done more easily is altering SS to maybe use not only shared cache but shared data as well - then webtop could be used for safe system, leaving more then enough space for it, and we still would have fairly usable 3.2 GB data for it. Maybe we could even assign preinstall as stock data? @Mentor.37, I'd really love to hear your opinion on this, or maybe even get your alternated safestrap's source so I could try it myself

Sorry guys, I'm dropping this. I tried CM12 in stock slot and it doesn't help the system as much as I hoped for, so there's no need for this from my side.
I also mistook the process of installing ROM in Stock. I thought I have to upgrade the stock system to the new ROM in order to keep Safestrap in it, but it turns out it's independent and when "wiping" stock /system it leaves the Safestrap there, so I can easily do a clean install of a new ROM in the stock slot

LuH said:
I tried CM12 in stock slot and it doesn't help the system as much as I hoped for, so there's no need for this from my side.
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About that, could you compare the difference regarding performance between CM12 on the safe slot and CM12 on the stock slot?
I currently got it running on safe slot but I'm thinking about trying to install it to stock slot, now that I sold my Lapdock and don't need Weptop mode anymore.
But I only would do it if it increases the performance of the D4.

Shani Ace said:
About that, could you compare the difference regarding performance between CM12 on the safe slot and CM12 on the stock slot?
I currently got it running on safe slot but I'm thinking about trying to install it to stock slot, now that I sold my Lapdock and don't need Weptop mode anymore.
But I only would do it if it increases the performance of the D4.
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Click to collapse
I don't really remember unfortunately, been running it from stock slot for a while now. Before it definitely was way more laggy than now, but that's also when CM12 for D4 was in a VERY early phase.
It definitely increases the performance, I'm just not sure how much. I don't see any reason why leave original system in stock slot though, so no reason to run CM from the safe slot. I don't like the idea of mounting the ext fs with system running from it from fat storage, it's bound to generate some unnecessary overhead.
In case of any major screw-up, sbf is your friend and AFAIK can't get messed up itself It's a good idea to have the factory cable available though, just in case it for whatever reason dies on you with low battery.

Ok, still good to know, thanks! What's sbf?
Well when I got my D4 a few months ago, I thought installing on the stock slot would be dangerous (in terms of bricking) and since I had the Lapdock, I wanted to keep the stock ROM.
But since then I've read that many users have CM12 running on stock slot, so now I want to do that, too. It's just so annoying when the whole phone freezes for half a minute or so and I think that's mostly due to the limited memory (although I have 170-300 MB free most of the time).
Do I have to consider anything special or different while installing than on an install on safe slot?

Shani Ace said:
Ok, still good to know, thanks! What's sbf?
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see
Q12: What is a SBF?

Shani Ace said:
It's just so annoying when the whole phone freezes for half a minute or so and I think that's mostly due to the limited memory (although I have 170-300 MB free most of the time).
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Same here, I suspect it's also connected with throttled data transfer requests of multiple apps at once, but the RAM is IMO the biggest factor. In Linux RAM is almost always full and the "free" space is occupied by cache (filesystem cache or whatever else app's cache) ready to be deleted - maybe the phone is stuttering when freeing the "free" space for other use.
Weird is that my brother with almost vanilla L 5.1 on Nexus 4 has system consuming about 100M less RAM than my CM12 - device-specific drivers maybe?
Shani Ace said:
Do I have to consider anything special or different while installing than on an install on safe slot?
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Click to collapse
If you mean on stock slot, just remember that you need to have some system installed there even in order to boot into safestrap - delete old, install new and ONLY then reboot, otherwise you're facing sbf Learned the hard way It doesn't brick your phone (meaning you can unbrick it), but it's lengthy and annoying...

@sd_shadow: Thanks, now I know. Feels kinda stupid having asked one of the FAQ's - can't remember when that happened before.
LuH said:
Same here, I suspect it's also connected with throttled data transfer requests of multiple apps at once, but the RAM is IMO the biggest factor. In Linux RAM is almost always full and the "free" space is occupied by cache (filesystem cache or whatever else app's cache) ready to be deleted - maybe the phone is stuttering when freeing the "free" space for other use.
Weird is that my brother with almost vanilla L 5.1 on Nexus 4 has system consuming about 100M less RAM than my CM12 - device-specific drivers maybe?
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Click to collapse
Ah that's interesting, didn't know that about Linux before. Well I always imagined that when there's little memory left, the drive somehow gets slowed down because there would'nt be enough space for some temp files or executions. But I don't really have a clue.
On the other hand, different devices showing different and inconclusive results like that is something I already experienced many years ago. ^^
LuH said:
If you mean on stock slot, just remember that you need to have some system installed there even in order to boot into safestrap - delete old, install new and ONLY then reboot, otherwise you're facing sbf Learned the hard way It doesn't brick your phone (meaning you can unbrick it), but it's lengthy and annoying...
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Yeah I know, I had read about it before. But you can't really miss all those hints everywhere, so I think the community takes good care of spreading that time-saving information.
Actually thanks for encouraging me, because last night I flashed CM12.1 and everything onto the stock slot! Today I installed and configured most of the things I needed (including int/ext storage swap) and I have to say, it really runs better! It might not be as smooth as with a more recent smartphone, but it's definitely snappier than CM12 on the safe slot was (now it's gone and will rest in peace^^). It may sometimes take a few seconds, but most of the time it's very fluid, a great, noticeable improvement.
Additionally, now that I don't have to household with the memory anymore, I installed all the apps that I had left out on the safe slot install and even installed a couple of huge games from the Play Store (NFS:MW, NBA Jam, Batman Dark Knight, Injustice) onto my microSD card and it still runs almost without any hick-ups! I haven't tested the games yet, though.
EDIT: It really seems to have something to do with the amount of memory left on /system. After all that installing I was down to ~ 200MB (which would've been normal on the safe slot) and the phone started lagging a little bit more. But after moving some games and apps to the SD I have more than 500MB 600MB - okay after deleting the cache it's 1,26GB - free on /system and the phone runs smoothly again.

Shani Ace said:
EDIT: It really seems to have something to do with the amount of memory left on /system. After all that installing I was down to ~ 200MB (which would've been normal on the safe slot) and the phone started lagging a little bit more. But after moving some games and apps to the SD I have more than 500MB 600MB - okay after deleting the cache it's 1,26GB - free on /system and the phone runs smoothly again.
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Click to collapse
I guess you're talking about /data, not /system (different partitions, /system is usually read-only and system is installed there with stuff you flash from safestrap, everything else goes to /data or /sdcard). Yup, when /data is becoming full, you're gonna experience some strange behavior.
/data is the first "Internal storage" in Storage settings, /system is not shown there, /sdcard is the second "Internal storage" and /sdcard-ext, or "SD card", is the actual microSD in default CM12 setup. I guess you have the last two switched though.

[Guide] Link2SD (or Apps2SD) on Galaxy Tab A (SM T-580)

Hello folks. Before going further I need to apologize. I really fighted to use Link2SD on my Galaxy tablet and I succeeded more or less. I thought that my tentative could be useful to others. So I posted this topic.
I worked a little more, and now I am convinced that I was wrong from the beginning.
The reality is that Apps2SD and Link2SD are obsolete utilities.
Forget creating a second volume on your external SD Card :
- Android/Samsung declare your SD Card as corrupted and always wants to reformat it.
- TWRP mounts the wrong partition and you have to manually unmout it and remount the good one
- The partitions need to be declared with a wrong type and this is really not clean
etc...
I suggest that you do not loose your time, forget Link2SD, and read this excellent topic:
https://www.xda-developers.com/divi...gles-fuse-replacement-will-reduce-io-overhead
My Galaxy tab A has only 11 Go available for the user. I bought a 128 Go external SD card to extend both /storage/emulated/0 and /data.
When you first install your SD Card, Android automatically mount this card as /storage/xxxx-xxxx.
This is a FAT volume extended on all your SD Card (128 GB for me).
This is fine for storing ebooks, music, video, and your backups.
But impossible for Link2SD to move your apps on this volume and put a symbolic link on the previous location, because FAT is not a UNIX file system. Link2SD (or Apps2SD) needs a second disk volume on partition 2 (/dev/block/mmcblk1p2) formatted with a UNIX file system (ext4 is fine).
Of course you need to have rooted your device. [A non rooted tablet is not better than a vulgar iPhone ]
To re-partition my SD Card I used ROEHSOFT PARTITION TOOL (SD-USB). (I tried unsuccessfully Aparted, it crashed every time I launch it). ROEHSOFT is convenient but tricky to be used by an advanced user :
- You cannot create a partition in a specific slot (for example /dev/block/mmcblk1p2): It automatically use first slot for the first partition you create, the second slot for the following partition, and so on.
- If you try to foul it, deleting a partition and recreating it in another empty space, it suddenly decides to reorganize your 4 slots. It really wants /dev/block/mmcblk1p1 to be the first partition on your SD Card, /dev/block/mmcblk1p2 the following, etc...
- You cannot create a partition at a specific offset inside an empty space.
After fighting with ROEHSOFT I finally won. I discovered too late that "fdisk" is part of BusyBox. If you know "fdisk" my advice is to use it instead of fighting with a software which pretends to be user friendly but is too limited.
OK, stop bla-bla and work.
1 - Dismount your SD Card : Parameters/Device Maintenance/Storage/Menu-Storage Parameter/Dismount
2 - Delete the only one partition
3 - For a misterious reason, my Android was not happy with his FAT volume on /dev/block/mmcblk1p1. Link2SD wants his UNIX volume on /dev/block/mmcblk1p2. So, if you use ROEHSOFT you need now to create a small dummy partition on /dev/block/mmcblk1p1. For me I created a 4 Go partition to be used by Linux Deploy. This partition needs to be declared as FAT32 (LBA) but should not be formatted as a FAT file system. EXT4 is a good choice.
4 - Create the second partition for Link2SD. I suggest not too much space for it, because you probably want a huge space for the third partion. This partition needs to be declared as FAT32 (LBA) but should be formatted with a UNIX file system. EXT4 is a good choice.
5 - Create the third partition to be used as SD extension for Android. This partition should be very large : you will store on it your music, your movies, your ebooks, and above all your backups. This partition needs to be declared as FAT32 (LBA). I formatted this partition as a EXFAT file system.
6 - Reboot. If you are lucky you will get two notifications : one saying that you have a corrupted memory card, and one saying that you are ready for media files. You will get those two notifications at each reboot.
8 - Recreate mounting scripts inside Lin2SD (or Apps2SD), and reboot.
7 - If you are a UNIX user just type "df -h" in a terminal to verify that the two partitions are mounted with correct sizes).
8 - You can look what Android think of your partitioning :
/Parameters/Device Maintenance/Storage/Menu:Storage Parameter/.
Do not try to mount the two first volumes and NEVER try to reformat them with Android. Those volumes are declared as corrupted but this is normal. Android does not expect to find a UNIX file system on a partition declared FAT32.
If one day, you forget this and ask to Android to reformat a corrupted partition you will have the terrible surprise that Android will not only erase your partition, but will erase everything and recreate one and only one big empty partition. (I guess that you keep all your backups on this SD Card, like me, so this is a really bad surprise).
Do not ask me why Android does not want his SD-Card on first partition. I have no idea. I guess that Android or Samsung reserve this partition for something else.
Do not ask why I had to declared all my partitions as FAT32 even if two of them are formatted as EXT4. I just realized that this configuration works well after fighting during a full day.
I hope that this topic will help some of you.

You really need the second partition on the SD? Or you can have only one ex4 partition that fills all the SD? (Remove the FAT and only have one ext4)

Palatosino said:
You really need the second partition on the SD? Or you can have only one ex4 partition that fills all the SD? (Remove the FAT and only have one ext4)
Click to expand...
Click to collapse
No, I tried but it doesn't work.
I found today a very interesting topic that I will try to master and hopefully wil, understand everything better :
https://www.xda-developers.com/divi...gles-fuse-replacement-will-reduce-io-overhead
Maybe I was wrong from the beginning : perhaps LinkSD and apps2SD are historic patch that are not useful anymore. Perhaps all the burden will be fixed easily just by not using those utilities anymore.
"sdcardfs" is something very new for me who is an old UNIX fellow. This seems to be a major improvement for Android.
I will update this topic when everything will be clear for me.

I didnt have this problem on android 6, but on android 7 . My phone wants to use ext4 as data partition and says its corrupted, link2sd detects this second partition normally, but my data partition fat 32 detected on phone settings and its says its ready but there is no option to mount it.
As far as i understand from this tutorial i need to make 1 fake ext4 partition say 1mb, then second partition ext4 for use with link2sd, and third partition fat32 for use as data storage ??
My phone is samsung j7 2016
So i did follow this , but now my phone wont detect fat32 and link2sd didnt detect 1 of other ext4 partitions

Looking for a definitive way to Root and use link2sd to have my SM-T580 use the SD as a primary parition for apps and data. Been researching and trying a dozen different methods already to no avail. Bonus if there's a way to roll it back easily. Am on the latest android release.
Thank you for all replies.

larpoux said:
I hope that this topic will help some of you.
Click to expand...
Click to collapse
You're my saviour, thank you ! I've been fighting on the same issue for days and didn't think about that trick to declare an ext partition as FAT32 !

I know you probably won't see this, but I just wanted to tell you how much I appreciated this guide.
I have a Galaxy Tab S3 and every since going to a custom rom, I haven't been able to get this working which was such a pain with less than 23 gb of storage. The Rom improved my performance far too much for me to change back and every guide I attempted pointed me in the wrong direction but finally, I'm able to use my 120 gb SD card which has made my tablet worth using again.
To anyone who may attempt in the future,
I'm using Android 9 + Magisk. Using the Advanced type Mount script was the only way it get it functioning but I've had no issues with linking apps and no message regarding a corrupted SD card. It can take a few minutes on boot for everything to properly load in, but the apps all update and there's no performance/loading time issues.
Thanks again!