The 10GB optional ports on PowerConnect 6224\6248 switches can be used to connect to any 10GB port, provided you have the correct module installed (SFP+\CX4\XFP and 10GbaseT). These are sometimes called uplink ports but there is no specific limitation on what you connect them for unless they are specifically used for stacking switches using the CX4 modules. They can be used to provide 10GB connectivity to servers with a 10GB nics if that's what you want to do. These are in addition to the 24 1Gigabit ports. There are only two of these ports, regardless of the connector type that you choose.
The 8024 is an all 10Gbit switch where all ports can be used to connect to 10Gbit nics, or used as inter switch links to other 10Gbit switches.
Since you want two hosts to connect to a storage server at 10Gbit you will need at least 3 10Gbit ports, if not more, as I'd hope that your storage server has more than 1 network port. If that is the case then the 8024 is the Dell switch you want. If your storage server only has 1Gbit connectivity then connecting the hosts via 10Gbit wont do much for you in terms of storage access but it might help a bit if you need to use those same connections for other network traffic as well. In any case if only your hosts have 10Gbit ports then the 6024 can be used to connect them at 10Gbit (with the appropriate 10Gbit module of course).
There are other issues that you should consider - NIC\HBA redundancy on the hosts, switch redundancy and redundancy within the "storage server" but that's a much larger discussion.