exchange 2010 hosting (multi tentant) possibilities to add 1 store per customer

Unfortunately not. The multi tenant solutions will distribute the mailboxes automatically and you have no say in where they end up.

Geminon; than it will be difficult to restore a mailbox for a user if there is one mailstore?

Don't see how it would be difficult. True, you'll be limited to the management shell but you get used to that xD.

Maybe you could clarify your question a bit?

It should be perfect to have one store per customer; the customer gets a standard drive with everything on it, including the datastore.

Now this is not ideal. When the second customer comes in, the datastore is extended and will grow.We will not know how many diskspace is taken per company..?

You can create a different mail database for each customer and just select the correct database when you create accounts

@Neilst:
Unless this changed in the last few weeks in a hosted (multitenant) exchange 2010 SP1 setup you create users through the Webportal and you cannot assign a database.

@thisis_it:
In a hosted setup you would create multiple datastores and limit the size of the mailboxes through the mailbox plan. You know the maximum amount of space the customer is allowed to take and in that way you can plan for the capacity on the storage side

Yes sorry I was miles away, thinking of too many things at once.

Figured as much :) It happens xD

geminon: so when creating a new orginazation in powershell, I have to give the customer a serviceplan that creates a new store ? Do you have an example ?

In a multi tenant environment you use a powershell command to enable a database for provisioning.

More info:
http://blogs.nelite.com/blogs/yvarloud/archive/2010/08/16/exchange-2010-sp1-exchange-hosted-a-k-a-multi-tenant-organization-part-1.aspx
http://technet.microsoft.com/en-us/library/ff923272.aspx
http://www.zerohoursleep.com/2010/10/step-by-step-starting-with-exchange-2010-sp1-multi-tenant-installation/

Geminon, thanks but I already saw those articles. No article has the solution of which serviceplan to use for 1 store per customer..

Geminon,

Thanks for your help. Than I don't need to search further

You cannot assign one store per customer through the web portal.
As it has been stated above, it arbitrarily assigns users to different stores.
The only way to correct this is to manually create a store and manually create each email from the CLI as assign it to that store.
I wouldn't recommend this as if you have issues with that store you will be bringing their entire organization down with it.
I am also assuming you have a clustered environment and have a DAG in place to replicate stores.
The service plans defines the limits of the mailbox accounts and nothing with regards to the information store.