Both "data is" and "data are" can be used. In everyday English, however, the noun "data" is commonly followed by a singular verb.

Both "data is" and "data are" can be used.

The data is/are stored in our servers.

In everyday English, however, the noun "data" is frequently followed by a singular verb.

The data is collected from a range of sources.

When it is used with a singular verb, the word "data" is being treated as an uncountable noun.

Your data is encrypted to protect it from unauthorized access.

While some people consider the use of a singular verb to be incorrect, it is quite common and completely standard.

The data has been analyzed.

Technically speaking, however, "data" is a plural noun. As a result, in scientific writing or formal contexts, it should be followed by a plural verb.

The data are analyzed and combined by a team of experts.