Database Info

[DEV] /cache converted to swap

So as we all know /cache is used for OTA updates which, when you have your phone rooted is useless.
What I'm wondering is why we can't use /dev/block/mtdblock4 (aka /cache) as a permanent onboard swap partition. Granted it will only give us an additional 30MB but the speed of this swap will be higher than that of our sdcard.
In order to test this we'll have to:
convert this partition to a linux-swap partition.
mkswap /dev/block/mtdblock4
update init.rc to no longer mount this as yaffs2
add this new swap space to the swap script
The issue is of course being able to run a partition utility on the phone. Second, if this doesn't work we don't have a way to format /cache back to yaffs2 (that I know of).
If you have experience with any of the issues I listed above please comment/post. If you don't have a clue please don't post so we can keep this thread clean. I would appreciate only experienced devs responding.
If this is possible it would benefit Hero/MotoBlur ROMS which are memory intensive.

For your second concern, why would we need to change it back to /cache? Just make it a disclaimer when people attempt this operation.
More importantly, I think the primary issue is that this is rom space is it not? Doesn't this portion of the memory have a limited amount of times that it could be written to?

Hmm why not trying "parted /dev/block/mtdblock4" in recovery? ;-)
rest would be easy.

Couldn't we use mkyaffs2img (in recovery /sbin) to turn it back into yaffs?

persiansown said:
For your second concern, why would we need to change it back to /cache? Just make it a disclaimer when people attempt this operation.
More importantly, I think the primary issue is that this is rom space is it not? Doesn't this portion of the memory have a limited amount of times that it could be written to?
Click to expand...
Click to collapse
Well my concern was if there was some adverse effect of removing /cache from the system we'd need a way to revert back.
I am not aware of any MAX amount of times that /cache can be written to.
*Edited*
Due to unintelligent comments and moronism prevalent in this thread, I removed a line from this post to keep us on track of what this thread was meant to discuss.

There's another thing:
Recovery can't be used without /cache !
So we need to convert back each shutdown and convert to linux-swap each startup..

dumfuq said:
Couldn't we use mkyaffs2img (in recovery /sbin) to turn it back into yaffs?
Click to expand...
Click to collapse
I hadn't checked in the recovery img for any yaffs2 utilities. But if that indeed does exist then this will be possible.
So then the issue would be, is this safe to attempt long term with the amount of writes being done to internal flash?

maxisma said:
There's another thing:
Recovery can't be used without /cache !
So we need to convert back each shutdown and convert to linux-swap each startup..
Click to expand...
Click to collapse
So I see recovery is using it but the only thing in it is the recovery logfile. Could we modify the recovery to read/write the logfile to system/sd/recovery or something, or is the cache used for other stuff as well?

Another idea:
Instead of using it as swap, what if we could find a way to use it as compcache space? That way we don't sacrifice any of the internal ram for compcache and still have compcache running

maxisma said:
There's another thing:
Recovery can't be used without /cache !
So we need to convert back each shutdown and convert to linux-swap each startup..
Click to expand...
Click to collapse
What part of recovery needs /cache ? Does the recovery img mount the /cache partition? I'm wondering if the recovery img could be modified to write to the ext2 partition such as /system/sd/cache .

persiansown said:
Another idea:
Instead of using it as swap, what if we could find a way to use it as compcache space? That way we don't sacrifice any of the internal ram for compcache and still have compcache running
Click to expand...
Click to collapse
This is actually a good idea and it'd be interesting to see which way would benefit us more.

shafty023 said:
What part of recovery needs /cache ? Does the recovery img mount the /cache partition? I'm wondering if the recovery img could be modified to write to the ext2 partition such as /system/sd/cache .
Click to expand...
Click to collapse
When you activate an option in recovery, for example install update.zip, it writes the command into /cache/recovery and does a "quick reboot", which reads out the command and does this.

ok first dont even try it would one
reduce life on nand
cause issues with flashing
slow down any thing accessing the nand.
to the person thinking the ram is using flash. you must have never been to high school cause even typing class explains what ram is. plus g1 has memory write speeds of about 120mb/sec thats sdram. swap will never replace ram 120mb/sec versus 6 is huge

if you want real improvements you must change the code to something more efficient.
less bloat
more native code
fewer clock cycles
improved app states(cache on sd that would save the state by dumping part of ram to load later reducing clock cycles and reducing ram)
and my favorite rewrite system libs and apps to include more native code and reducing ram usage.
btw native code is about 10-100x faster than android java. that means 10%-100% more speed(or less load)

you could make a swap file and put it on there and just mount the file...........

yeah what he said!
zenulator said:
you could make a swap file and put it on there and just mount the file...........
Click to expand...
Click to collapse
This sounds like a good idea, altho we would have to get compcache working with backing swap file.
do we know if the /cache speed is compaired to Class 6 microSD?

good luck hardheads

jokersax11 said:
ok first dont even try it would one
reduce life on nand
cause issues with flashing
slow down any thing accessing the nand.
to the person thinking the ram is using flash. you must have never been to high school cause even typing class explains what ram is. plus g1 has memory write speeds of about 120mb/sec thats sdram. swap will never replace ram 120mb/sec versus 6 is huge
Click to expand...
Click to collapse
Dude honestly get a life. I have a Bachelor's degree in Computer Science. And I could code in Intel Assembly accessing each and every register in memory while you're left googling what Intel Assembly code means. Maybe you should keep up with the latest technology. If you did you'd know there are all-in-one memory chips that support NOR, NAND flash, and RAM.
http://www.eetasia.com/ART_8800466798_499486_NT_ab9e537f.HTM

jokersax11 said:
if you want real improvements you must change the code to something more efficient.
less bloat
more native code
fewer clock cycles
improved app states(cache on sd that would save the state by dumping part of ram to load later reducing clock cycles and reducing ram)
and my favorite rewrite system libs and apps to include more native code and reducing ram usage.
btw native code is about 10-100x faster than android java. that means 10%-100% more speed(or less load)
Click to expand...
Click to collapse
Exactly what type of "native code" are you referring to? And do you have any idea what type of memory the G1 uses for RAM? Go back to your typing class.

Shafty did you see Zenulator's idea? That seems like it could work.. Does the phone ever format the cache partition?

[Q] Q. Regarding Data Storage on BootMenu's 2nd System

I posted this in a thread in the Dev. section but that's probably not the appropriate place for it - I've been installing ROMS (SCV7, Swifty Trix) with BootMenu on the second system with Leak #1 on the primary system. On the primary system I have ~ 4 gigs allotted to app storage and on the second I only have ~ 200 mbs. I can't even begin to install a basic set of application... are there any suggestions on how to remedy this situation? I've been Google-ing the subject but haven't found much information so far.
EDIT - So, I guess "RTFM" should always be in mind:
Q: I have a "low storage space" on 2nd system?
Webtop partition size is only 1.3GB.
To make thing simple, the included boot_second.sh script bind mount /system & /data inside this webtop partition.
You have at least 4 option, if you want to have bigger /data
1.Reassign /data to /sdcard (IO speed depend on sdcard speed rating)
2.Reassign /data to /dev/block/userdata (this will replace all your data for stock system)
3.Reassign /data to /dev/block/cache (bind /cache to somewhere else e.g : /webtop/cache)
4.Use a lightweight ROM (/system size = small)
You need to modify these files to suit your needs.
/preinstall/bootmenu/script/boot_stock.sh
/preinstall/bootmenu/config/stock.recovery.fstab
/preinstall/bootmenu/script/boot_second.sh
/preinstall/bootmenu/config/second.recovery.fstab
Sorry, for now you all have to configure this files manually.
--------
So, this is a little beyond what I've done with Android thus far... for now I haven't been able to figure out how to work it out. Any suggestions would be much appreciated. Thanks!

goto
1) mounts/format
2) format webtop
3) toggle second system recovery (main menu)
4) install/restore whichever ROM u desire
i think erasing webtop will pretty much free system space in "second system"
and remember second system is usually considered as trial purpose
as far as my exp. changing something in first system will somtime affect the second system
Happy flashing

aguacateojos said:
I posted this in a thread in the Dev. section but that's probably not the appropriate place for it - I've been installing ROMS (SCV7, Swifty Trix) with BootMenu on the second system with Leak #1 on the primary system. On the primary system I have ~ 4 gigs allotted to app storage and on the second I only have ~ 200 mbs. I can't even begin to install a basic set of application... are there any suggestions on how to remedy this situation? I've been Google-ing the subject but haven't found much information so far.
EDIT - So, I guess "RTFM" should always be in mind:
Q: I have a "low storage space" on 2nd system?
Webtop partition size is only 1.3GB.
To make thing simple, the included boot_second.sh script bind mount /system & /data inside this webtop partition.
You have at least 4 option, if you want to have bigger /data
1.Reassign /data to /sdcard (IO speed depend on sdcard speed rating)
2.Reassign /data to /dev/block/userdata (this will replace all your data for stock system)
3.Reassign /data to /dev/block/cache (bind /cache to somewhere else e.g : /webtop/cache)
4.Use a lightweight ROM (/system size = small)
You need to modify these files to suit your needs.
/preinstall/bootmenu/script/boot_stock.sh
/preinstall/bootmenu/config/stock.recovery.fstab
/preinstall/bootmenu/script/boot_second.sh
/preinstall/bootmenu/config/second.recovery.fstab
Sorry, for now you all have to configure this files manually.
--------
So, this is a little beyond what I've done with Android thus far... for now I haven't been able to figure out how to work it out. Any suggestions would be much appreciated. Thanks!
Click to expand...
Click to collapse
All of that is not needed, and you will mess up your install on first system too.
I get trying new things out and trail blazing, but next time do a little research first. There are people who don't think and search for a problem and find your solution try it and learn they now have to fxz, but don't know how or can't.
This appears to be way beyond you. Next time try something a little smaller and less likely to screw something up for those that don't know or not very capable.
shardul.phatak said:
goto
1) mounts/format
2) format webtop
3) toggle second system recovery (main menu)
4) install/restore whichever ROM u desire
i think erasing webtop will pretty much free system space in "second system"
and remember second system is usually considered as trial purpose
as far as my exp. changing something in first system will somtime affect the second system
Happy flashing
Click to expand...
Click to collapse
What he said ^^

[SWAP] Swap on Internal * v0.5 alpha *

SWAP on internal
Extend your RAM with very quick internal SWAP
v0.5 alpha​
For the moment, the script is confirmed to work only on ROMs with the chinese x-part (or data2ext) by Atroy script only (read at the end of this post for alternative).
The only ROM I am aware of using this script out of the box is the excellent MIUI XJ x-part.
However, I intend to develop a non-loop based version shortly. It should will be compatible with most ROMs, so stay tuned.
What and Why
I decided to make a script that places the swap file on internal memory. Many people place it on SD card, but to me it seems somewhat pointless, as it hardly offers sufficient performance.
However, placing it on the internal memory makes it a much more interesting concept, because it has much better random read/write performance than even the fastest SD cards.
Warning: placing SWAP on internal memory will subject it to frequent read/write operations which in theory shortens lifespan of internal memory chip which you cannot replace. This is because flash memory has limited number of write/read cycles to it. So, consider yourself warned.
HOWEVER:
1 - although true, in reality I have been unable to find any case of this actually affecting anyone's phone. There is very limited amount of data documenting real-life effect of that process, but most likely your device will be long gone before the internal memory will show any signs of wear.
2 - the script recreates the swap file on each boot using different physical blocks of memory - this means not the same blocks are always used. More on this in 'Do it right' section.
Do It Right
1. 16-32 MB of swap should suffice. If you think you need more, you are probably wrong. NEVER use all available internal space. The larger the proportion difference between swap size and total free space on the internal data partition, the more breathing space your internal memory gets, as this allows the swap file to be moved around upon every reboot, which, in turn, will make it use the same blocks more rarely, and thus extending memory chip lifespan.
2. Get rid of bloat you don't use from the system partition, ie: ringtones, live wallpapers, useless system apps. Then create a custom
hboot with smaller system partition and larger data partition. You can do it using this (also attached to this post).
3. Play around with swappiness parameter. Still, the default set by the script should serve you well. But if you are paranoid, you can use it to further decrease how often system will write to swap.
Removal
Disable execution flag on the scipt in /system/etc/init.d and delete swap.img from internal data directory (on x-part scripts it is /mnt/asec/mtddata/ )
v0.5 alpha
* first public release
* loop device version only
Click to expand...
Click to collapse
x-part Impacted script (80% chance of rendering your ROM unbootable)
I attached a data2ext script which should offer better performance and battery life than some other a2sd scripts.
You are free to try and flash it on your ROM, but there is a good chance it won't boot any more - this is a very alpha version and I am not working on it at the moment.
Do not post complaints about it here. I only want to hear from you if it works!

So this allocates a part of your internal memory for random access? Nice.
I personally don't need more RAM, but this could be useful.

This sounds really good to my ears :good:
I will keep an eye on it.
Edit:
A small question:
So is it possible to use this for any rom if you are using data2ext for it?
Or atm only for miui xj?

Androidmarketuser said:
A small question:
So is it possible to use this for any rom if you are using data2ext for it?
Or atm only for miui xj?
Click to expand...
Click to collapse
You have to use Atroy's data2ext, which is virtually impossible to obtain because it was developed as part of chinese MIUI rom and never released as a separate script.
However, I have been working on it and I am attaching an alpha version of my adaptation of this script to the first post
Let me know if it works, but there is a good chance your ROM will not boot any more.

impactor said:
However, I have been working on it and I am attaching an alpha version of my adaptation of this script to the first post
Let me know if it works, but there is a good chance your ROM will not boot any more.
Click to expand...
Click to collapse
Thanks for your answer
I tried to install it on CM10 by vj but it didn't work. Here are my steps:
Wiped everything except sd
Installed rom, then data2ext script and finally the swap script.
I'm on a ext4 partition if it matters.
I think (not really sure) one script has created two folders: /data/ and /data-app/ on sdcard.
Or did I just install it the wrong way?
Edit: The problem was as you expected that it stucked at HTC bootlogo.

Androidmarketuser said:
Edit: The problem was as you expected that it stucked at HTC bootlogo.
Click to expand...
Click to collapse
If you want to try x-part script, then do not flash swap script until you confirm the x-part rom works.
Try with some GB rom. Maybe you'll have more luck.

impactor said:
If you want to try x-part script, then do not flash swap script until you confirm the x-part rom works.
Try with some GB rom. Maybe you'll have more luck.
Click to expand...
Click to collapse
I'll try it out that way on JB first (I am addicted to the new design, can't go back:crying, if it doesn't work I will try it out with 2.3 anyway.
---------- Post added at 08:45 PM ---------- Previous post was at 08:31 PM ----------
Ok on JB the data2ext script doesn't seem to work, I can't boot.
I will try it out later with a GB rom, propably EuroSkank

Hmm still doesn't work.
I tried MW7 on Redux2 but stucks at boot logo...

Custom hboot maker link from thalasmus blog is dead!
Can someone plz attach it here!
Sent from my HTC Desire using xda app-developers app

vasili_defy said:
Custom hboot maker link from thalasmus blog is dead!
Can someone plz attach it here!
Click to expand...
Click to collapse
Attached.

Don't have swap on internal! The number of read/writes will just kill your nand by creating loads of bad blocks.
Just my 2 cents
Kind Regards
Dave

topgeardave said:
Don't have swap on internal! The number of read/writes will just kill your nand by creating loads of bad blocks.
Just my 2 cents
Click to expand...
Click to collapse
And pray tell, apart from hearsay, what else do you have to support the claim that it will occur within foreseeable lifetime of the device?
I'd love to learn.

impactor said:
And pray tell, apart from hearsay, what else do you have to support the claim that it will occur within foreseeable lifetime of the device?
I'd love to learn.
Click to expand...
Click to collapse
After flashing ROMs on my Desire for nearly 2 years I'm starting to get bad blocks on my nand. Having a swap partition on internal would accelerate the process of getting more bad blocks. That's what I think anyway. Check your recovery.log for bad blocks next time you wipe your phone.
Kind Regards
Dave
Sent from my HTC Sensation using xda app-developers app

I tried this on Alex-V 1.8 and nothing happened
probably did something wrong
I'll try again later

topgeardave said:
After flashing ROMs on my Desire for nearly 2 years I'm starting to get bad blocks on my nand. Having a swap partition on internal would accelerate the process of getting more bad blocks. That's what I think anyway. Check your recovery.log for bad blocks next time you wipe your phone.
Kind Regards
Dave
Click to expand...
Click to collapse
Thanks for the heads-up. But I gave a clear warning about in the first post. After two years, my desire has 4 bad blocks, which amounts to less than 0.5mb of internal space (less than 0.1%). Everyone should make a concious decision about using internal swap.
It will degrade the memory chip, yes, but is the degradation significant enough to care? Everyone has to decide for himself.

impactor said:
Thanks for the heads-up. But I gave a clear warning about in the first post. After two years, my desire has 4 bad blocks, which amounts to less than 0.5mb of internal space (less than 0.1%). Everyone should make a concious decision about using internal swap.
It will degrade the memory chip, yes, but is the degradation significant enough to care? Everyone has to decide for himself.
Click to expand...
Click to collapse
how can I check if it's running on my rom...?

Balino said:
how can I check if it's running on my rom...?
Click to expand...
Click to collapse
Go into terminal and run "free"

impactor said:
Go into terminal and run "free"
Click to expand...
Click to collapse
It says swap 0... I think woh's roms doesn't support swap....

[Q] One S space used by stock rom.

I was looking on the storage tab and I saw 4gb space taken by .. something.. I am curios , what could take so much space ? I have a database server running centos that takes less. Anyway , I havent rooted my phone yet and I am curious . Anyone could tell me what is there eating so much space ? Also with custom rom can you free more space from that ? I come from Desire S, there the stock 4.0.4 rom was using 5-600mb .

That "Other" is probably a load of cache and data that has built up over time and that you've never bothered to delete. At least 1GB of that will be Facebook if you are a heavy user.
Sent from my One S using xda premium

The phone is 5 days old. And no I don't use facebook , those 4gb in other remain there even after factory reset. That is why I am asking.

icrazy said:
The phone is 5 days old. And no I don't use facebook , those 4gb in other remain there even after factory reset. That is why I am asking.
Click to expand...
Click to collapse
You can try clicking the make more space button and clearing some apps' cache.

icrazy said:
I was looking on the storage tab and I saw 4gb space taken by .. something.. I am curios , what could take so much space ?
Click to expand...
Click to collapse
4.50 / 6.07 is just not true. You do not have 6G of app storage. You have about 2.50G.
So it's possible that you have about 1G used, and therefor about 1.50G free. (If they calculate used space from free space plus an assumption of total space..)
The layout is:
10G - sdcard
2.5G - data
1.7G - system
0.25G - cache
rest - sbl, hboot, boot, recovery, radio, wifi, modem, splash, ...

Touch of jobo what you say makes sense , but I just dont understand what can be in /data to eat 2.5gb or in system to eat 1.7gb

icrazy said:
Touch of jobo what you say makes sense , but I just dont understand what can be in /data to eat 2.5gb or in system to eat 1.7gb
Click to expand...
Click to collapse
Those 2.5GB and 1.7GB for data and system respectively are the partition sizes. It doesn't necessarily mean they are full. (In fact, they are not.) It means we could technically flash ROMs that have up to 1.7G of /system. (Currently, ROMs take only up to about 700M tho.)
I believe that you have about 1GB of apps and app data on your /data partition, so about 1.5GB of /data free.
-Jobo

You should download a file manager and have it inspect your SD card to see what's on it and in your internal memory(Not sure if Stock Sense had something like this) I used ES File Manager and it gives you a pretty layout showing what's using what

Thanks IntelligentAj very good ideea . Look at the 2 screenshots taken with sdmaid . The partitions look different and some space is not there
later edit.
Actualy I took it to calculator .It adds up to 5273 mb , is close enough I guess. Should help if anyone else has questions on stock JB partitions .
Sent from my HTC One S using Tapatalk 2

I would strongly recommend rooting your phone though and installing a custom ROM. Stock Sense is exponentially slower than pretty much all custom ROM's

I will root it no doubt about it . I have a desire s and lenovo tablet all rooted . But with this one is more complicated .. I have to keep it untouched for some time. And I was curious about the space .

Oh I was worried when I first rooted my phone but they have all in one tools or you can do the actual adb stuff, which isn't hard at all as long as you follow directions
Sent from my One S using xda app-developers app

[Q&A] 2 GB External Data -- Hefe Hook Kernel and others

The Hefe Hook kernel allows you to mount a partition of your microSD as /data, getting 2 GB (or more) for your apps and their data.
Please ask your questions here about installation, use, or general approach.

This is great @jeffsf and can u show me how to re-partition the "real internal" storage? I mean expanding the /system since u put the /data out of it. Thanks man
Sent from my GT-N7000 using Tapatalk 2

daothanhduy1996 said:
This is great @jeffsf can u show me how to re-partition the "real internal" storage? I mean expanding the /system since u put the /data out of it.
Click to expand...
Click to collapse
Yes, you've hit on another of the reasons I've been exploring using the microSD for "live" storage. It's one thing to use potentially slow storage for photos that you basically write once or "app to SD" where you read the APK at boot time, make sure your ODEX in the Davlik cache is good, then generally read from the internal-flash cache. It is another when that memory is being read and written "constantly" when your phone is running.
The good thing is that once /data is not part of the internal flash filesystem, you don't have to worry about one ROM (kernel) thinking it begins at one place and another saying it starts at another. Previously, if one ROM had one /system size and another and a different one, the next partition, /data, would look to be corrupt when you swapped ROMs.
As a warning, not all users have fast microSD cards. Some that say "Class 10" on them really are dogs, especially for small reads/writes. The "Class" ratings are for sustained writes, as you would have with a camera recording video. If your ROM is "external /data" only, or even defaults to that, be prepared for a slew of "Your ROMs sucks. It is so slow." complaints.
You'll also need a way to automate formatting the card. It can be done on the phone, as long as you aren't trying to preserve any data.
As I recall, the layout of the MTD partitions is done in drivers/mtd/onenand/samsung_galaxys4g.h I would be careful not to move the partition boundary for efs, as you'd have to move the data it contains in your updater script. Repeating the warning about not moving the boot and recovery partitions is probably a good idea as well!
Your build tree may need some of these values, or at least think it needs some of these values. For example, device/samsung/aries-common from the CyanogenMod/cm-11.0 (KitKat) branch calls out NAND page sizes, partition sizes, and flash block sizes. I haven't looked in detail at your build tree so I can't comment on how it might handle things differently than the CyanogenMod one.

itzik2sh said:
Hi
I hope I don't ask anything silly, but please let me know if any of my assumptions is wrong :
1. I take FBi's251's AOKP milestone 6 (ICS 4.0.4)
2. 8GB SDCard was formatted to FAT32 (4GB) and EXT3 (4GB) using TWRP kernel
(Beastmode's proton kernel to be exact).
3. I would flash this kernel and it would move apps and their data to the sd-ext
without any special additions.
Thanks. I read the thread, but unfortunately 8GB SD is what i have and I think it should be enough.
Thanks again.
P.S - it's for 2 guys I already sold them my SGS4Gs. I want them to be happy...
Click to expand...
Click to collapse
AOKP should be fine. I haven't tried it recently, but it was the tree in which I did the early Hefe Kernel development.
As I understand it, you have a microSD with
partition 1: 4 GB FAT32
partition 2: 4 GB ext3
So that can work, but will need some tweaking of the init-on-fs.sh script. I intentionally didn't use the second partition as so many scripts gobble that up as sd-ext and do who knows what to it.
My first preference would be to reformat the cards, perhaps:
6 GB FAT32
1 MB ext2/3/4 (Yes, 1 MB, a sliver, choice of ext2, ext3, ext4 up to you)
2 GB ext4
since then the script will work without modification and if they install a third-party script that uses the second partition, it won't corrupt their data.
If you were to keep the formatting the way that it is now, you'd need to edit the mount commands in the script to look something like:
Code:
/system/xbin/busybox umount /data
/system/xbin/busybox mount -t ext3 -o noatime /dev/block/mmcblk0p2 /data
(removing the sd-ext mount)
I'm not sure what your expectations are, but all that the kernel and that script will do is mount a different disk partition on /data -- you need to manually move the data over (or restore from something like Titanium Backup). There may be some trickery in renaming that could be used with TWRP backups to restore from data.yaffs2.win to the new /data partition, but I haven't tried that at all.

Hi Jeff
Thanks for your quick reply, and sorry again for not seeing the Q&A thread.
I think making it :
partition 1: 4 GB FAT32 (sdcard)
partition 2: 2 GB ext3 (sd-ext)
partition 3: 2 GB ext3 (data)
partition 4: 1 MB (spare)
would be better and handle data as well. don't you think ?
Would it be worth doing with a "Team" micro-SD card (class 6 I believe) ?
Thanks.

I haven't tried a Class 6 card, but my gut feeling is that it will be dicey. I didn't "commit" to using /data on microSD until I had tried it for several days using Titanium Backup's ability to move both apps and app data to the external card. I would try that first, especially as the phones in question aren't going to be in your hands (I consider you an expert user, able to manage things outside the UI with ease).
I've attached some testing I did a while ago with Transcend and SanDisk cards. When you look at them, realize that the speed scale changes between them. I have a feeling that the real "performance" on a device is going to be related to relatively small reads and writes, not the ability to stream video to the card. I also don't know much about the Team brand, but I found that even some well-known brands didn't have the performance of the Transcend or SanDisk in the same category.
However you configure your cards, I would definitely recommend a journaling filesystem of some sort. I've had my microSD come loose inside the phone. The journal will at least help to reduce any filesystem corruption should that happen.
You don't need the fourth partition -- I have it there to be able to keep rsync backups for fast ROM swapping.
.

Regarding the apps data, have you tried exploring the Mount2SD script ?
sent from me

I've tried a couple of the scripts out there in the past. Since backing up my data is very important to me, I trust the scripts in Titanium Backup to work well with its backup/restore strategies.
Mounts2SD looks like it has gotten a lot more sophisticated than it was when I tried it in the past. It sounds like something worth trying in its current state. At a quick glance (and not looking at the code), I'd personally make some different choices about features; enabling journaling, and being concerned about why lost+found was filling up (things should only appear there if the file system is found to be corrupt).