There was a nice thorough discussion of backups for non-rooted (and maybe also locked) devices here. Most of that covered Android 4.x+ because of the use of
adb backup, which apparently doesn't exist in prior versions. A second question on backing up 2.3.x under the same conditions, found no answers.
I'm am dealing with Honeycomb 3.2.6, which I have not yet unlocked, and I am considering the last answer at the first link. I am considering if there is a way to, possibly temporarily, boot a recovery to do the backup. I can see three possibilities:
(1) That answer suggests connecting via USB with Debugging enabled and then:
abd reboot bootloader
fastboot boot twrp.img
As opposed to
fastboot flash recovery twrp.img, that should temporarily boot the twrp.img without changing/wiping /data. From there it should be possible to do a nandroid backup to an SDCard. The author of that idea didn't seem to have tried it themselves. I wonder if anyone has, and if it's likely to work as described.
(2) According to the TWRP website for this device, if I
fastboot flash recovery twrp.img and then on reboot press the proper key combination to enter the recovery (in this case power+volume-down), then
Note many devices will replace your custom recovery automatically during first boot. To prevent this, ... find the proper key combo to enter recovery. After typing fastboot reboot, hold the key combo and boot to TWRP. Once TWRP is booted, TWRP will patch the stock ROM to prevent the stock ROM from replacing TWRP. If you don't follow this step, you will have to repeat the install.
Is this true for TWRP on all/most/many devices?
(3) Another approach to temporarily booting a recovery, mentioned in one of the comments at that first link, is to boot one off of an SDCard. I found one example in another device I have. I'm wondering under what conditions that might work and how to arrange it? If anyone has any insight, I would also appreciate them.