4-Way Data Buffering
For maximum protection against loss of data, the PDC persists (stores) the real-time data stream
from each EMS Host to both the EMS Host disk and all Pegasus Server Rings, in real-time. In the
event of Network Failure, Pegasus Data Server Failure, or Pegasus Data Server maintenance,
collected data continues to be buffered on the EMS Hosts. On Network and/or Pegasus Data
Server restoration, the Pegasus Data Server Buffers are automatically synchronized with the
EMS Host Data Buffers.
In the event of failure of the EMS Primary Server, Pegasus Data Servers automatically switch to
and synchronize with the Backup EMS Server’s real-time data stream, with no increase in load
on the EMS Servers or the Pegasus Data Servers. In the event of both EMS Primary & Backup
Server Failure, Pegasus contains a mirror copy of the real-time data stream from both the
Primary & Backup Servers up to the point of failure(s), to assist in Catastrophic EMS Host
Failure.
In the event of EMS Primary failure while the Network is unavailable or the Pegasus Data
Server(s) are offline, no data is lost. Pegasus automatically re-synchronizes its data buffers to
match the EMS data buffers, detecting which sets of data were from the “then” Primary EMS
Servers. Multiple EMS Host transitions can occur while the network to Pegasus is unavailable, or
the Pegasus Data Servers are unavailable, without loss of data from the Enabled Host.
Additionally, all Pegasus Binary Data Files (called HSBs) comprising the 4-Way Data Buffer are
binary compatible across all supported operating systems and all Habitat versions. This
insures Electric Utilities can use previously captured EMS data when EMS Hosts are upgraded to
newer or different Hardware and/or Operating Systems.