ARM/N900/DataManagement

Revision as of 12:13, 9 June 2011

Introduction

One of the most important aspects of a working system is Data Management. During the lifetime of a running system, data and configuration details are setup with the expectation that they are secure.

Ensuring that the data you create and configure on your device is sustained is a high priority. The notes on this page are a starting point to ensuring the various aspects of this are catered for.

The scope of this document is currently aimed towards the N900-DE, however the principles are expected for MeeGo globally.

Please help to expand upon this document

Single partition installation vs Dual Part installation.

Maemo device installation consists of 2 parts:

• RootFS Code partition.
• eMMC Data Partition

MeeGo Installation consists of 1 part:

• RootFS Code + Data Partition.

With Maemo, it is possible for the Backup tool to store User data onto the eMMC and ensure that between installations the data is safe and can be restored from.

MeeGo however has no such ability. Even the Netbook is an all-in-one installation. This causes serious problems for data during updates or reinstallations. The following application requests and points are based around having this problem solved.

The N900 device is *lucky* to have the eMMC available (even if not used at present) Other MeeGo devices may not have such a device/data storage area available.

Backup/Restore application is needed.

Now we can get on networks and get past initialisation issues, a mechanism to Backup/Restore data between reflashing is necessary. Added complexity for N900-de is that the whole "image" is on one partition which is overwritten by each image flashed.

• Possibilities
  • Use eMMC from maemo to store MeeGo N900-DE backup data files
  • Change the N900-DE image so that MicroSD is partitioned into Code (regular flash) and Data (similar to eMMC)
  • make a compatible data Backup/Restore application and store alongside Maemo backup files (very hard)

A suggestion from IRC:

• <KaIRC> lcuk: and given that YaST package manager is also a graphical frontend to zypper nowadays, I would think MeeGo can do things similarly - but yes, nicer interface is always good :)
• <lcuk> if you can make it work on n900-de I would like some screenshots
• <KaIRC> lcuk: well, YaST is the integrated system management tool in openSUSE, I have no idea if or how it would run on MeeGo

Maemo Data Import is needed.

Similar to the Backup/Restore application.

This would require the Maemo Sharing to be functional first.

• Mechanism to Import some or all of the Maemo data:
  • Import Contacts
  • Import network settings
  • Import SMS messages/Conversations
  • Import Misc application settings

SSU is needed.

Now that we are doing more and filling in data, a mechanism to update is required.

• Start with a daily/weekly image
  • Open Application "System-Update"
  • Check for updates, compare on device repository against latest available system

Maemo Data Sharing is wanted.

To access realtime and safely the data stored on the eMMC live and direct.

• To allow sharing the data from Maemo side.
  • Photographs and videos taken with the device camera
  • Music and example files.

Accessing the partitions

Quick discussions in IRC asking how to proceed:

• <lcuk> from standard n900-de, does anybody know the "mount" commands required to mount: eMMC and maemo rootfs?
• <lbt> lcuk: use dmesg to identify the block devices
• <lcuk> lbt do they all show up?
• <lbt> then mkdir a target dir like /mnt/maemo and /mnt/mmc
• <lbt> they should, yes
• <lcuk> ok thanks, will investigate
• <lcuk> I am going to try first to see about accessing them
• <lbt> then mount /dev/device /mnt/place
• <jsv> lcuk: "cat /proc/self/mounts" on maemo5 console shows what's where. you should be able to ignore the bind mounts
• <jsv> also, before you ask "mount -t ubifs ubi0:rootfs <mountpoint>" for rootfs on NAND

merlin1991 highlighted this thread: http://forum.meego.com/showthread.php?t=3511

<lcuk> jukkaeklund, <lcuk> osso-backup appears to be closed source (the maemo backup tool) <lcuk> I wonder what would be required to tweak within that to run on n900-de <lcuk> obviously it is hildonised, but that is less of a tweak than rewriting from scratch <lcuk> hm

http://maemo.org/packages/package_instance/view/fremantle_ssu_pr1-2_armel/osso-backup/1.8.20-1+0m5/