[Optimus One, P500, V Q&A, Help & Troubleshooting] Dovidhalevi:
As we know, JB and Kitkat ROMs have gotten much larger than their ICS predecessors. Flashing these and some gapps can easily run our device out of space on the system partition. Some apps will not even be installed, others will have errors. Even some hardware may not work correctly. So the ROMs must be trimmed to fit correctly.

In higher-end devices, they will be 1GB of system space. ROM-builders and chefs tend to dump everything on system as a convenience. Flash the ROM, a load of gapps and one has a complete-functioning system. What could be simpler?

For our oldie-but-goodie, we do not have this luxury. Even with micro-gapps consisting of an old Play/phonesky.apk and some framework will run out of space.

Really, anything not needed to get Android up and running does not need to be on system. There are some additional apps that require extra permissions afforded system apps to work. They need be kept there as well. But the others? Install as user apps. Then let link2sd or such symlink them out of the way (data space runs out too easily on our old phones as well!)

I trim the ROMs to bare metal. Not necessary to be so severe however. I ran ICS for a long time with 3 meg on system with no problems.

What do I remove, keep, etc?

1. /system/usr/srec (speech recognition stuff, most likely no longer in use!) I keep a copy on sd-ext and symlink to there. No problems.

2. Ringtones, alarms, sounds -- most of these have already been trimmed off the ROMs by the devs so I leave what they leave. Want more? Place in similarly name folders on the sdcard and Android will find them.

3. Fonts:

Linux, Android, XDA, are international communities. To save a small bit of space, non-Latin fonts have been removed from recent CM-11 and Omni ROMs. I objected, placed revert request on Jenkins. Raise those voices, folks. Many of us regularly use non-Latin fonts and languages. I keep all the fonts. The fairly large "fallback" font is usually missing on ROMs nowadays. Those using CJK languages or getting a lot of '?' in text should put it back.

4. Apps, apps, apps:

Calendar should be installed from Play. Take off ROM.

I install Apollo, Calculator, CMFilemanager, Cameras, Galleries as user apps. Work fine.

If one does not use live-wallpapers, take their apps off.

If one is using Google Search/Now (must be side-loaded as not fully compatable with our device and will not install from Play), the QuickSearchBox is no longer needed in system.

Google Play Services can be installed as a user app and auto-updates as such anyway. A version of Play, older and smaller the better, apparantly must be on system but the full newer versions should be installed as user apps and will be auto-updated as such.

Flash the tiniest gapps one can. Most all gapps such as Maps, Keep, Hangouts, etc., etc., are installable from Play as user apps.

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5. Keyboards

The LatinIME with all the languages was ridiculously large. Recent ROMs only have English. There are numerous kbs on Play. One only needs a small kb on system to enter Google account on first start if one wiped data. Do not need swipes, handwriting, voice, dictionaries, etc. Since I do not wipe data, I do not even keep the LatinIME. But better to have a kb on the ROM.

Want swipes and languages without the bloat? Try multiling-o. Whole business is 330k and numerous!! languages install as user apps as well and do not eat up data space. Not quite as good as Swype or Swiftkey but pretty close, very light-weight, and very configurable as well. Note that recent paid link2sd versions can symlink app data as well so one can now have one's Swype or Swiftkey and eat it to :)

Interest in other's ideas and alternatives!