What are we looking at here? This is the free space of the various mount points of the phone. System is the OS (Android 4.0.4 in this case) and SD should be fairly self-explanatory.
The 147MB data segment is the space for storing apps. It’s supposed to be 512MB, but HTC did something funky… and a lot of the default apps take up space here, so there is really not a lot of space for third party apps. The first thing you do when installing a new ROM on the Desire is to create a new Ext partition, and start linking parts of your data mount to it.
As with all things Android, there’s a choice of what to move off to your partition: Apps, Data and Dalvik Cache. Moving Apps to Ext is essential, but at the same time, doesn’t help much. After four or five apps, I’m still out of space on my Apps partition.
I decide to move Data but it doesn’t help much. This screenshot shows the result after moving data – and data still has 128MB used of 147MB. Surprise surprise – Dalvik Cache is also stored in “Data”.
Unfortunately, moving Dalvik Cache pretty much hoses your performance. It contains pre-compiled byte code and loading that off SD card takes a long time. Apps start taking between 10 seconds and a minute to start-up.
I’m caught between a rock and a hard place. Truly awful performance, but plenty of space for apps. Or moderately poor performance and no space for apps.