Ok since iam currently developing a Magento Clearcache Module, that handles Memcached, Redis and Apc i ran across your problem and could maybe help you out:
Lets start with:
<force_standalone>0</force_standalone>
0 is for standalone PHP
but in most cases you will use
1 for phpredis
which means with 0 you wont be able to connect to redis from php since the wrong adapter is selected.
From your local.xml i assume you'r using Cm_RedisSession as well ?
if so, what will the following command bring up to you:
connect the redis-cli to your redis server and:
info keyspace
if you now get:
"#keyspace"
db3:keys=405,expires=23,avg_ttl=7197349
that means, that your sessions are stored within redis but the backend isn't.
If so feel free to drop a short message here and we can go on from there.
Best Answer
Both Redis 2.8 and 3.0 is supported by Magento 2
Difference: Redis 3.0 supports up to 64 different databases per instance of the service, while 2.8 allows for only a single database
Reference: http://devdocs.magento.com/guides/v2.0/cloud/project/project-conf-files_services-redis.html