With the release of OTA-4 a few weeks ago, we received a few reports of
problems where the handset would get stuck in a boot loop, or refuse to
boot past the initial logo.
One root cause we have established is when the system partition has run out
of space.
Given that the supported model for system updates is that only the
system-image-updater writes to this space, it does not display a warning in
the case when the disk has been filled by something else.
We've got to this root cause unfortunately quite late in the ota-5 cycle,
so we didn't have time to land any engineering fixes (indeed, we're still
discussing what might be possible).
Of course, if your system partition has been writable, I think you have
taken on some measure of responsibility for looking after your phone, so
can you do something before an OTA? Yes - you can check for a reasonable
amount of free space.
If you've made your system writable, I'm going to assume you can use
terminal or adb on the command line.
Use df to see how much space you have:
$ df -h
/dev/mmcblk0p6 2.0G 1.6G 460M 78% /
<more lines skipped>
You only need to be concerned with the space assigned to / (rightmost
column). The other columns may differ on each machine. Here you can see the
results from my machine, and from a 2G partition, around 460M is free. This
will be fine for OTA update, since this machine has only ever had a
read-only system partition.
Specifying how much space you need for an OTA update is tricky - once
you've made your disk writeable, maybe the OTA will need a different amount
of space, because some of the files you've updated share footprint with OTA
delivered files.
If you use your system in a writeable mode, and have had OTA updates
delivered successfully, please comment here with how much disk space you
have/had free.
