APPLICATIONS
AND DATA:
Océano will support
an improved version of the AFS file system. Our goal is
to investigate the scalability, availability and manageability of the
shared data on a large-scale dynamic server farm. Dolphins will run
as
Linux hosts but their applications are installed on an AFS cell. This
allows a single point of installation and management for the application
setup, and a short deployment time for new Dolphins when they are
dynamically added to service a customer. This approach requires some
extra
steps when bringing up the Dolphins, and a somewhat modified application
installation procedure. A special installation procedure is needed only
for
those RPMs that are not "relocatable". By using AFS, Dolphins
can become
dataless machines - almost everything they need (applications executables,
configuration files and data) is stored on the AFS servers (Whales),
while
the local disk is used only for the basic OS and utilities and for
temporary storage (swapping, caching, logging, etc). The performance
degradation normally felt by diskless machines is avoided by AFS aggressive
caching policy, i.e., at the steady state most data is local to each
Dolphin. Moreover, the typical high demand on network bandwidth of diskless
machines is also reduced dramatically by the AFS caching policy. Océano
will improve this even further by reducing the time it takes to reach
this
steady state through pre-loading the AFS cache (priming) and multicasting.
