  Indra is a suite of large-volume cosmological $N$-body simulations with the
goal of providing excellent statistics of the large-scale features of the
distribution of dark matter. Each of the 384 simulations is computed with the
same cosmological parameters and different initial phases, with 1024$^3$ dark
matter particles in a box of length 1 Gpc/h, 64 snapshots of particle data and
halo catalogs, and 505 time steps of the Fourier modes of the density field,
amounting to almost a petabyte of data. All of the Indra data are immediately
available for analysis via the SciServer science platform, which provides
interactive and batch computing modes, personal data storage, and other hosted
data sets such as the Millennium simulations and many astronomical surveys. We
present the Indra simulations, describe the data products and how to access
them, and measure ensemble averages, variances, and covariances of the matter
power spectrum, the matter correlation function, and the halo mass function to
demonstrate the types of computations that Indra enables. We hope that Indra
will be both a resource for large-scale structure research and a demonstration
of how to make very large datasets public and computationally-accessible.
