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- Communication is through TCP/IP sockets and makes use of secure
sockets and compression.
- The servers employ a sophisticated API for housing servlets and
managing the requests to the installed servlets, using load-balancing
as needed.
- Servlets can be installed on any number of servers in any location.
- Rather than require that a hole be poked through the firewall of
the back end for each server, the system was designed with two
types of servers: the Master-Server and the Sub-Server.
- Although any number of Master-Servers can be configured, the
Master-Server primarily routes requests to the appropriate Sub-Server
containing the necessary servlet that has been called.
- Servers and Master Servers have no GUI and can be configured to run
as a Windows service or Unix-type daemon. All configuration is
handled remotely through use of the Server Manager application.
- Note that all configuration of the server and servlets is done while
the server is running "hot", allowing for little or no down-time.
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- The Storage servlet allows access to "virtual" volumes of shared
storage devices. To a client application a "virtual" volume appears
as a single volume with up to Terabytes (or more) of disk space.
- However, the underlying storage can be spread across any number of
servers and shared devices (in a platform independent manner).
- Writes can be duplicated for data safety, and volumes can be copied
or migrated to different devices while the servers are running "hot".
- The actually configuration information for the shared devices are
stored in the database so is available to any Storage servlet on
the system.
- Writes to sub-storage devices can be configured to write to the
devices sequentially (i.e., fill up devices in order for contiguous
storage) or in a round-robin fashion (for faster read/writes).
- Writes and reads can also be configured to duplicate data to multiple
locations. Sub-storage devices can be enabled or disabled, to prevent
reads and/or writes from occurring on the sub-storage device.
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