Deduplicating file systems - example

Last published : Jul 06, 2026
Storage Foundation 7.4.2 and later enables customers to use file system deduplication to optimize existing primary storage. Enabling deduplication at the file system layer results in storage savings and avoids complex and expensive appliances typically associated with file deduplication.
Deduplication is performed without needing any application changes and with minimal overhead. Deduplication does not change the file extension, allowing users and applications to use files normally, without performance effect.
The VxFS deduplication feature works as follows. It eliminates duplicate blocks used by your data by comparing blocks across the file system. When the deduplication feature finds a duplicate block, it removes the space used and instead creates a pointer to the common block. If the duplicate file is changed, thus making the files no longer share the same block, then that changed block is saved to disk instead of the pointer.
For more information on how deduplication works, see the following topic:
See About file system deduplication.
Using the InfoScale Operations Manager Management Server console you can enable file system deduplication and view the space savings.
Requirements for deduplication
Deduplication has the following requirements:
  • InfoScale 7.4.2 or later.
  • File System (VxFS) disk layout version 9 or later.
  • InfoScale Operations Manager managed host (VRTSsfmh) version 7.4.2 or later.
Use cases for deduplication
The following are good candidates for deduplication:
  • Virtual machine boot image files (vmdk files)
  • User home directories
  • File systems with multiple copies of files
The following might not be the best candidates for deduplication, as they have little or no duplicate data:
  • Databases
  • Media files, such as JPEG, MP3, and MOV
Example of using deduplication
In the following example, a storage administrator has a volume and file system that are set up to store multiple copies of documents in a source control system.
The following object names are used in this example.

Table: Example names

Object Name
Host lnx_host
Volume vxvm_source_control
Mount point (file system) /user_source
The administrator performs the following procedures to reduce storage waste with file deduplication.
Locate the volume and mount point for the directories to undergo deduplication
Implement deduplication
Verify the results of deduplication
To perform deduplication operations, you must have administrative privileges in InfoScale Operations Manager for the host on which you invoke the deduplication operation.
Locate the volume and mount point for the directories to undergo deduplication
To locate the directories in InfoScale Operations Manager, you need to be able to identify the volume and mount point (file system) by name. The following procedure explains how to use the Management Server console to locate a volume and mount point for a host.
You can also use Search on the console menu bar to search for a volume and mount point.
To locate the volume and mount point
  1. In the Management Server console, go to the Server perspective and expand Manage in the left pane.
  2. Click Data Center and on the Hosts tab, type all or part of the host name to filter the list of hosts. For example, typelnx_host. Double-click the host name in the table. The host is highlighted and expanded in the tree.
  3. In the tree, under the selected host, click Volumes.
  4. On the Volumes tab, filter the list of volumes to locate the volume. For example, type vxvm_source_control.
Implement deduplication
InfoScale Operations Manager lets you implement deduplication for a selected file system. You configure the deduplication database and optionally set up a schedule.
To implement deduplication for a file system
  1. In the Management Server console, locate the volume and mount point. For example, locate vxvm_source control (/user_source).
  2. Right-click the volume on which the file system is mounted and click Properties.
  3. Click the Deduplication tab.
  4. Click Configure.
  5. In the Configure Deduplication window, you can customize the following options:
    Enabled If you clear the check box, the deduplication operation is disabled. If you want to enable it later, return to this window.
    Data Usage Lets you optimize the database size according to the type of data and the amount of space available for the database. The smaller the chunk size that is selected for data, the more space is required for the database. Once configuration is complete, this parameter cannot be changed except by unconfiguring the database and reconfiguring it.
    For most data, InfoScale recommends the default, Other (16k) .
  6. To set up a schedule for deduplication, select from the following:
    Commit on run number The deduplication process scans and fingerprints the data before eliminating duplicates. You can schedule the deduplication process to eliminate the duplicates each time it runs (the default value of 1) or every specified number of times. During the times that deduplication does not
    occur, the deduplication run only updates the fingerprints in the database.
    Weekday Schedule You can select one day of the week or schedule a run every day.
    InfoScale recommends that you schedule deduplication when the system activity
    is low so as not to interfere with the regular system workload.
    Hours Schedule the hour to begin a deduplication run.
  7. Click Finish. The deduplication configuration sets up the deduplication database. When a message shows the configuration is complete, click** Close**.
  8. If you want to run deduplication now, rather than wait for a scheduled time, click Scan Now. Click** Yes** to confirm that you want to begin the deduplication. Once it is begun, you can close the window. The operation runs in the background.
Verify the results of deduplication
You can verify the results of deduplication for a specific file system on the Deduplication tab.
The Space Saved field shows the most recent savings. You can also view savings over time under Space Saved History. To change the time period, select from the Duration drop-down list and click Apply.
You can also run a report to view top savings for file system deduplication.
To run a report on savings by file system deduplication
  1. In the Management Server console, go to the Server perspective and expand Reports in the left pane.
  2. With the Storage Utilization category displayed, click the Savings by File System Deduplication report.
  3. In the Select Scope to run report wizard panel, select the scope of the report and click Run.
More Information
Examples: Identifying and reducing storage waste using InfoScale Operations Manager