With my hands on the pre-release for a couple of days of the Android 4.3 Sense 5.0 update that will be available sometime in the future from Sprint, I’d noticed a problem I hadn’t considered before. The update wipes all data on the internal SD card in order to repartition the HTC EVO 4G LTE’s storage to something somewhat sane.
The HTC EVO 4G LTE shipped with 16GB of internal storage, on which a gig or two was devoted to the ROM image, another two gigs devoted to storing cache and apks, and then about 12 gigs of storage devoted to pictures and misc stuff.
What that lead to was a device with a lot of storage that ran out of space quickly because only two gigabytes was devoted to applications, data, etc. You could move applications to the external SD, but you’d find on updates they’d move themselves right back in, and not everything plays nicely with being moved. You’d also just fill up quickly because some applications are huge.
This has been corrected in the new update with a remapping of the partition layout to provide a ROM area of it appears 2.24 gigabytes, and an internal+media storage space of 12.4 gigabytes.
To remap these partitions, everything on the internal storage of the device is destroyed by the firmware update, and then you come along and push a ROM image into the now-blank space.
So unless the firmware that we have in the prerelease is completely different than what will be released, this probably is not going to be doable via OTA, and will most likely wipe what you’ve got on the phone.
Technically it’s doable – download ROM, firmware to SD-EXT assuming you have one, backup all information (contacts, applications, etc.) over there, flash firmware, install ROM, restore contact, applications, etc. But not everyone purchased an external SD card for their EVO 4G LTE, so you can’t assume they’re planning for that.
So my best bet is that this is not going to be released OTA, but RUU, meaning you’ll download an application from HTCDev or Sprint, and to get the update you’ll need to back up your data to a computer, run the RUU, and then restore.
I think this is why we’ve had this delay.
I could be wrong, and they might decide to create a temp partition, move the backup data to it, shuffle things around as new partitions are created and old ones deleted. It is possible to do this without data loss, but I guess we’ll just have to wait and see.