Having had the opportunity to work on a new build using Magento 2 the architecture of the application has changed significantly, to me it has definitely increased the difficulty of getting a Magento project up and running but in return offers a more granular and organised application to work with.
With this view I think it’s unlikely that you would upgrade your site to v2. Magento have not given an upgrade path to 2.0 and I doubt they will, so it’s probably worth waiting for the opportunity to re-design the site before moving over to the new platform.
Magento have committed to 3 years from general release of 2.0 so that gives you till around 2019 to move over. In the meantime that means they will continue to provide security patches and support for the 1.x platform.
Step 1- Enable maintenance mode
cd /magento_folder
#for example: cd /var/www/magento
touch maintenance.flag
Step 2: Manually you can take backup of your database and directories
Make sure you take the full backup of your store’s database and directories.
Step 3: Commence the upgrade process
cd /magento_folder
rm -rf var/cache/* var/session/*
chmod -R 777 /magento_folder
chmod 550 ./mage
./mage mage-setup .
./mage config-set preferred_state stable
./mage list-installed
#In case, modules are not listed, use the below given command to upgrade further:
./mage install http://connect20.magentocommerce.com/community Mage_All_Latest --force
#And if your Magento modules are listed – use the following commands:
./mage list-upgrades
./mage upgrade-all
#Once the upgrade process is done, you’ll see a list of modules – ‘already installed’, ’package upgraded’, make sure your permissions are set back to normal:
php shell/indexer.php reindexall
chmod -R 644 ./*
find . -type d -exec chmod 755 {} \;
chmod 550 ./mage
Step 4: Go live with your website
cd /magento_folder
rm -f maintenance.flag