I've read somewhere that I can do some certain things to partition my SD Card specially to allot some part or all of it to trick the phone into thinking it's the "internal" ROM. For the life of me, I can't seem to locate that article anymore. I'm looking forward to rooting my phone and this has been on one of my to-do list once I get around to rooting.

The next issue I want to bring up is that, once I've achieved the above procedures, I typically won't be using my phone's original internal ROM anymore and was thinking if it was possible to allot that unused internal ROM as additional RAM. So in essence, my phone's internals will only be used as RAM and the ROM will be the SD card's burden.

That way, I can hopefully maximize my phone's usability. Can anyone shed some light on this?

  • I guess you mean "RAM" rather "ROM"? RAM: Random Access Memory; ROM: Read-Only Memory. Does not make sense to turn your SD into a ROM. In any case, what are you exactly trying to achieve? – Stefano Jun 20 '12 at 7:58
  • @stefano He means what he wrote. For some reason (possibly historical) the internal flash memory is called ROM in the android community. – R R Jun 20 '12 at 10:00
  • @RichardBorcsik , I am no expert of Android Community Vocabulary, but do you have any pointer to support your claim? To my knowledge, ROM is used mostly as a short for "ROM Image" - not for the Internal Memory itself as a whole. My personal opinion is that using ROM for Internal Memory is wrong and source of confusion. The internal memory is a Flash one, eg. (E)EPROM – Stefano Jun 20 '12 at 10:08
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    Calling the internal Flash a ROM isn't so wrong. There are /boot, /system and radio sections that won't be written to usually. Nowadays, real ROMs don't exist any more. Almost everything moved to Flash (NAND or NOR) since the late 80's (replacing (E)EPROMs). – ce4 Jun 20 '12 at 14:36
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    @ShedoSurashu I agree that RAM isn't correct in this case either, sorry I added confusion with that. Internal Memory still sounds much better than ROM to me. But hey, I come from a different world ;-) @ ce4 real ROMs indeed have almost always been write once or write few; still find confusing calling the internal memory a ROM. These are pointers I found: what is a rom, ROM and Kernel, and of course wikipedia – Stefano Jun 21 '12 at 8:56

I think you are referring to a hack commonly known as "Apps-to-SD" (a.k.a. "apps2sd" or "a2sd" on some forums). This is where you re-partition your SD Card to have an Ext2/3/4 partition after the main Fat32 one, and then use a custom ROM/kernel combination that allow moving certain parts of OS to that partition. Namely, all 3rd-party downloaded apps, phone's cache, and in some cases app data and dalvik-cache.

Also keep in mind that as with all custom ROMs and kernels, this needs to be built for a specific device, so you will need to find a ROM with built-in Apps-to-SD support for your specific handset.

This trick does free up a portion of internal memory for use as RAM. However, as with most such solutions there are many cons to be aware of.

  1. SD Card needs to be re-partitioned in a very particular way (data will be lost during partitioning, so back it up.)
  2. Speed rating of the SD Card will play a large role in the system's overall performance and stability. Slower cards will cause delays in apps starting up, for example.
  3. The phone will not be able to function if you remove the SD Card, since the 2nd ext partition is now used by the phone as if it was part of its internal memory.
  4. Extra wear and tear on the SD Card from excessive writes. Unlike the EPROM in Flash memory, the SD Cards aren't really designed for many write cycles, so as time goes on you will find the card wearing out sooner than usual.
  5. Device will not be as stable. You may see ANR (application not responding) messages more often, as even the fastest SD Cards are still much slower than the internal flash memory.
  6. Data corruption on the SD Card is a real issue, and can render your phone inoperable, requiring a complete re-flashing of the ROM and loss of all data. So have recent backups always, and preferably not on the SD Card itself.
  • Well, to be honest, I just wanted to make it so that all apps I install will be placed on the SD card. I'm sure you are aware that if I do the "Move to SD Card" approach, some parts of the app still remain on internal memory, (Facebook, for example, still leaves around 2 or 4mb on internal storage.) So I want to make it so that all applications I install will be contained on the SD, thus making my phone only limited by the size of the SD card. As of right now, I'm limited by the ROM so being able to move it all to SD would be a great since I can always upgrade to a bigger one. (32gb) – Propeller Jun 20 '12 at 15:52
  • And also, I plan on using a class 10 microSD. Will that be of any good? – Propeller Jun 20 '12 at 15:54
  • In that case I must refer you to this question: android.stackexchange.com/questions/9767/… – Chahk Jun 20 '12 at 15:54

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