[DISCUSSION][POLL]interest in running ics/jb off SD?

**bigsupersquid** · 11-20-2012, 07:27 PM

so, I've seen a few mentions of this but no real discussion.
rave, bash, or question, as you prefer.

in a nutshell, it's possible to modify or preempt init to mount the sd card before mounting the system partition.
this would allow moving /system/app (and other space hogs) to the sd-ext partition, making install space and other possibilities potentially very large.
you want a fast card (class 4 or higher) and you can't remove it while booted (except in recovery.)
regular ics or jb for our device requires the card to boot anyway, and probably to run correctly as well, so it wouldn't be a huge change there.
any thoughts/opinions?
there's a poll, too.

**bigsupersquid** · 11-20-2012, 07:37 PM

the main pros seem obvious, increased storage for system apps and freeing the space they take up in NAND.
the cons, as I've read, are several
already mentioned, card can't be removed.
card has to be better than stock for decent speed.
ext2 has potential for data corruption in a crash.
ext3 or ext4 can wear out your card with the journaling which helps prevent the ext2 problem with crashes.

**A-android-B** · 11-20-2012, 08:17 PM

I am way interested and I have an eight gig class 4 in my zv5 optimus v, I would be honored to test and report log cat screenshots error messages , what have you! Please hit me , knowing you if you even mentioned it you already have a test build rolling

come to the dark side

**A-android-B** · 11-20-2012, 08:20 PM

And I was on a ubuntu forum and someone mentioned formatting to ext 4 but somehow disabling journaling to get all the speed improvements and such from ext 4 but be faster, use less power too

come to the dark side

**flapjack.fiasco** · 11-20-2012, 08:21 PM

Definitely interested. Anything that keeps this little phone rolling a little longer.

Sent from my LG-VM670 using Tapatalk 2

**ThatGuyLurkin** · 11-20-2012, 08:27 PM

Nice to see your still posting here. Seemed as if you were gone for along time.

I'd be interested in seeing this, although I don't use SD-EXT swaps or whatever you wanna call it. :P

**joemac84** · 11-20-2012, 08:53 PM

Sounds good to me. I was initially opposed to this idea but, WTH. Why not try it andd see how it works

**A-android-B** · 11-20-2012, 09:02 PM

Anything2ext has worked good for me so far without any stability issues.I've been using an ext partition ever since the early days of Bobz cm9

come to the dark side

**upconvert** · 11-20-2012, 09:40 PM

I would love to try something like that. It seems like if someone knew a little about mounting scripts, it would be easy enough to apply it to any of the billion roms for this phone as a simple proof of concept. I would absolutely test if someone could build that rom.

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**thewraith420** · 11-21-2012, 06:36 AM

Ics runs well enough just using ext for apps and dalvik but I'd be interested to see what this concept could do for jb or in the future key lime?

Tapatalk'n it from my Cold As Ice VM670 running LS670ZVJ firmware

**flapjack.fiasco** · 11-21-2012, 07:37 AM

Originally Posted by thewraith420

Ics runs well enough just using ext for apps and dalvik but I'd be interested to see what this concept could do for jb or in the future key lime?

Tapatalk'n it from my Cold As Ice VM670 running LS670ZVJ firmware

I still hold out hope that they're going to call it key lime, but that easter egg in JB insinuates something else.

Sent from my LG-VM670 using Tapatalk 2

**sgeoxd** · 11-21-2012, 09:07 AM

This is done by using "writeback" as the data mode. Kernel documentation on the subject is available at

Benchmarks usually show minimal difference between writeback and ordered, where some of the benefits of journaling can be retained with ordered. A few examples:

Using noatime, nodirtime, and disabling barriers can also improve performance. Found a link to instructions Android specific here:

**adamhos** · 11-21-2012, 09:56 AM

I would try
Sounds like a very cool idea

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**thesaxphoner** · 11-21-2012, 10:31 AM

I'm definitely interested, I tried doing this myself a while back but it didn't go well. I've got a 32gb class 10 so speed isn't a problem

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**flapjack.fiasco** · 11-22-2012, 09:17 AM

Originally Posted by thesaxphoner

I'm definitely interested, I tried doing this myself a while back but it didn't go well. I've got a 32gb class 10 so speed isn't a problem

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I've read previously that class 4 may in fact be better than class 10 in these situations, because they tend to have a faster random read/write speed as opposed to faster read and faster write speed. I could be wrong, but I think I read it in the context of booting a ROM straight off the sd-card.

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**bigsupersquid** · 11-22-2012, 12:49 PM

there's the "security issue," also, of whatever bits of system are moved to SD, being r/w rather than read only.

while I haven't built anything yet, I was assessing whether anyone but me had info./desire on this.
it'd most likely be easiest to move all of /system to the SD card rather than parts of it.

the mod would most likely be a severely trimmed version of tasssadar's multirom which patches the ramdisk with preinit (mounts sd-ext) and init.rc tweak (mount system from sd-ext.)

Not sure, but might well need a specialized recovery too, again tweaking tasssadar's work would probably be easiest.
<edit> on the bright side, it could be a fakeflash recovery (thanks to koush, a fakeflash recovery runs from a zip in recovery but doesn't replace the installed recovery to do it,) so you could leave whatever recovery you like installed and just use the mod recovery when you need it.
just thoughts so far, nothing concrete.

and, sgeoxd put up a he**uva first post.

**tvall** · 11-22-2012, 05:28 PM

here's an idea. Put what would normally be on /system in a file on /sd-ext. you'll have to mount /sd-ext earlier in boot then mount the system image and you would have to modify a gapps installer, but installs would be copying a single file, and you can keep the system mounted ro.

**bigsupersquid** · 11-22-2012, 07:25 PM

a loop-mounted filesystem?
I don't remember if I got those to work in init.rc or not.
but there is a squashfs loop-mount commented out in all the cyanogen init.rc's I've looked at, so it might well work as you say.
Worth a shot if my current avenue gets too annoying, or as a cross-check with benchmarking to see which prevails.
thanks for the input.

**droiddekka** · 11-22-2012, 08:07 PM

um.

yes.

**thesaxphoner** · 11-23-2012, 12:13 AM

You could be right, I'm not sure. I know that I used to use a class 2 and bobz cm10 worked fine on it but when I went to this all my apps that were on /sd-ext worked way better than before. Mine is also UHS-1 but I don't think the v can handle that.

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**bigsupersquid** · 11-23-2012, 12:17 PM

after much wankiness, I am running bobz cm10 completely from a class 4 16 GB card using tasssadar's multirom.
had to install it to NAND and SD from zip, and then manually copy it from /system, /data, and /cache to the card after a first boot using ADB in recovery.
multirom is not very happy with it, for some reason /system gets remounted r/o somewhere after init.rc runs, and when /system is made r/o it remounts the rest of /sd-ext r/o as well. so later in the boot from sd, I have to use adb shell to remount /system as r/w.
however, it is using the full size Gapps, market works, and I installed all the stock live wallpapers I could find to /system/app just for fun (I found 5, black hole, phase beam, nexus, bubbles, and water.)
I'm poking around at it now testing... I just remember the ril data glitches annoyed me in this rom last time I tried it.

**Encerspay45** · 11-23-2012, 01:52 PM

Great idea.

**glarepate** · 11-23-2012, 03:33 PM

Originally Posted by bigsupersquid

a loop-mounted filesystem?
I don't remember if I got those to work in init.rc or not.
but there is a squashfs loop-mount commented out in all the cyanogen init.rc's I've looked at, so it might well work as you say.
Worth a shot if my current avenue gets too annoying, or as a cross-check with benchmarking to see which prevails.
thanks for the input.

Would that just require a kernel with the loop driver already in it rather than being loaded during the init process? Just guessing ...

I am running the mirage 2.6.32.9-073012 kernel in my ROM:

the loop driver isn't being loaded as a module:

# cat /proc/modules
# [null output]

# cat /proc/filesystems
nodev sysfs
nodev rootfs
nodev bdev
nodev proc
nodev cgroup
nodev tmpfs
nodev sockfs
nodev pipefs
nodev anon_inodefs
nodev inotifyfs
nodev devpts
ext3
ext2
ext4
nodev ramfs
vfat
yaffs
yaffs2

There could easily be a reason why it isn't normally included in the kernel and I wouldn't know.

But perhaps other kernels include the loop driver.

**tvall** · 11-23-2012, 04:02 PM

All the kernels I've seen support loop if I remember correctly.

I know that loop mounting /data works. I once had my /data in a luks container. Had to modify the init.rc a lot to get it to work, but it worked well.

**bigsupersquid** · 11-23-2012, 07:05 PM

I also believe loop is built in and enabled by default.

Code:

ls /dev/block/

and look at all the loop devices.
thekraven's CAI with virgin patch runs nice off sd like Bobz cm10, with the same weirdness about remounting /system r/w through adb to get boot to complete.
and removed the a2sd scripts from init.d since it's already using the sd-ext for /data and dalvik.