Chapter 3 DXi3500 and DXi5500 Remote Management
Data Services
Quantum DXi3500 and DXi5500 User’s Guide
101
De-duplication Policy:
Data de-duplication works by recognizing repeated
blocklets
in a steam of data. Only a single instance of each blocklet is
stored and references (tags) are made for all of the duplicate blocklets.
These references or tags are stored in an index for use later to reconstitute
the de-duplicated data. By only storing one instance of the blocklet, a
great deal of capacity is saved. For a virtual tape cartridge, the DXi
system waits for 30 seconds of inactivity before a file can be de-
duplicated. For a NAS share, the DXi system waits for 60 seconds of
inactivity before a file can be de-duplicated.
Truncation Policy
: Another way the DXi system reduces the amount of
filesystem capacity used is to truncate the deduplicated data. Once the
deduplicated data is truncated, only the metadata is available on the
filesystem. This reduces the amount of capacity required in the
filesystem. Once truncated, the file must be reconstituted using it’s tag
before you are able to access the file. The DXi waits for a period of
inactivity for a file before it truncates the file. For a virtual tape cartridge,
the DXi system waits 90 seconds before it truncates the file. For a NAS
share, the DXi system waits 120 seconds before it truncates the file.
The
Space Management
page is divided into the following sections:
•
System Usage
•
Space Reclamation
System Usage
3
The
Space Usage
pages allows you to set notifications and define the
system usage threshold. The threshold is the percentage of filesystem
capacity at which a notification is automatically sent to the user. Crossing
the threshold does not stop normal processing. An informational
message or trap is sent when the filesystem usages is within 5% of the
threshold. A warning message or trap is sent when the threshold is
exceeded.
To configure space usage:
1
From the
Space Management
page, click the
Space Usage
link.
The
Space Usage
page displays (see
figure 58
).
