American Megatrends ManageTrends 2.7, Руководство пользователя

Страница: 319 / 367

Appendix I : Continuous Data Technology 301
StorTrends iTX Installation CDP implementation uses an efficient and innovative “N-
Way” I/O router module that can be configured in the run time to offer efficient I/O
journaling by eliminating unnecessary data copies and reducing extra I/O overheads. This
results in improved I/O latency.
During a Review or Rollback operation, initially a rollback to a previous writable
snapshot is done and then the redo Journal is played on top of it to the selected point in
time.
Under the hood: StorTrends iTX Installation CDT
The Advanced Caching Module of iTX stack serves as the central repository of in-flight
data. In addition to many advanced caching functions, this module also implements a “N-
Way” data router that allows incoming data to be multiplexed out to various data
handling and transporting modules. This helps in effectively channeling data with Zero-
Memory-Copy. Therefore, incoming data can be routed out to a remote recovery site (2A)
as well as captured by the Journal Module (2B), as shown in Figure 6 below.
The Journaling module timestamps the arriving data and stores them in the journal files
giving it the essence of Time-Addressable-Storage (TAS). This module also exposes an
event registration interface through which relevant events can be tagged and stored. The
figure shows snapshot events (C) generated by Distributed Volume Manager (DVM) And
other application specific events e.g. database checkpoints (D) are recorded in the Event-
Addressable journal.
At the heart of the technology resides the CDT engine. This works as the client of the
Journal and snapshot modules. When historic data is requested, it gives a very fast access
to the data using a very dense and efficient in-core index table. Powerful APIs and CLIs
are offered to locate, review and rollback the requested image.