我无法在 Ubuntu 上安装 datastax cassandra 2.0。我可以毫无问题地安装 2.1，但我需要运行 2.0.9。我正在按照这些步骤操作，我可以做些什么来安装 2.0 吗？
echo "deb http://debian.datastax.com/community stable main" | sudo tee -a /etc/apt/sources.list.d/cassandra.sources.list
curl -L http://debian.datastax.com/debian/repo_key | sudo apt-key add -
sudo apt-get update
sudo apt-get -y install dsc20
错误是：
$ sudo apt-get -y install dsc20
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
dsc20 : Depends: cassandra (= 2.0.10) but 2.1.0-2 is to be installed
E: Unable to correct problems, you have held broken packages.