BackBox H4.00 User Manual

Product Description
19 BackBox H4.00 User Manual
3) Using the BackPak GUI, Volume tab, the operator initiates the materialization
of a volume (Volume Materialization) or a batch of virtualizations (Virtualize
Volume), monitors the status of these tasks, and eventually, if needed,
cancels them.
Details about the physical tape attachment are provided in Appendix B – External
tape devices installation.
General guidelines for migration to BackBox are provided in Appendix C – Migration
to the BackBox product.
Windows Files Data Store
In this type of Data Store, a virtual volume is implemented as two Windows disk
files:
A small index file containing metadata (file name *.IND).
A variable length data file, whose size is based on the current content of the
volume (file name *.DAT).
A Windows Files Data Store is defined as a pool of disk paths entered in an UNC
syntax (\\server\path\[directory\]. Although very special contexts (single VTC) could
support the drive letter (D:\directory\), UNC is recommended for all cases.
If the distinct hardware disk units are not hidden behind a merged logical disk, the
emulator will manage to provide:
Storage space balancing across disks
Load balancing across disks
Fault tolerance for writing SCRATCH volumes
While writing and reading these Windows disk files:
For a volume to be loaded for write, the VTC allocates a file sized according
the configured maximum volume size plus a margin of error of 10 MB.
Unused space is freed at volume unload.
The possibly configured compression does not change the file size, but the
amount of NonStop data contained in the volume.
When the Data Store is configured across a pool of disks, the emulator may
move the files of a virtual volume from a disk to another to balance storage
space or work load. A file can be moved:
o When a SCRATCH volume is being written and the auto-scratch
mechanism is enabled, the files are recreated in the optimal
location
o When a restore script is executed, the files comprising a volume
are restored in the optimal location
The user can change the load balancing default algorithm to force usage of
local disk independent of any other consideration, using a parameter of the
Data Store configuration.