Update archipelago documentation

docs/archipelago.rst

@@ -3,4 +3,20 @@
 Volume Service (archipelago)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-`Coming Soon ...`
+Introduction
+============
+
+Every Volume inside a VM can be thought of as a linearly addressable set of
+fixed-size blocks. The storage of the actual blocks is orthogonal to the task of
+exposing a single block device for use by each VM. Bridging the gap between the
+VMs performing random access to Volumes and the storage of actual blocks is
+Archipelago: a custom storage handling layer which handled volumes as set of
+distinct blocks in the backend, a process we call volume composition. For the
+actual storage of blocks we are currently experimenting with RADOS, the
+distributed object store underlying the Ceph parallel filesystem, to solve the
+problem of reliable, fault-tolerant object storage through replication on
+multiple storage nodes. Archipelago itself is agnostic to the actual block
+storage backend. 
+
+Archipelago is under active development and will be available soon.
+