Administrator Guide
Steps
1 If you are connected to a Data Collector, select a Storage Center from the drop-down list in the left navigation pane.
2 From the STORAGE menu, select Volumes.
The Volumes view is displayed.
3 In the Volumes view, select the volume you want to modify.
4 Click (Edit).
The Edit Volume dialog box opens.
5 Expand the Data Reduction menu.
6 From the Data Reduction Input drop-down menu, select a Data Reduction input.
• Inaccessible Snapshot Pages – Data frozen by a snapshot that has become inaccessible because other data has been written
over it
• All Snapshot Pages – Data frozen by a snapshot
7 Click OK to close the Edit Advanced Volume Settings dialog box.
8 Click OK.
Compression
Compression reduces the amount of space used by a volume by encoding data. Compression runs daily with Data Progression. To change
the time at which compression runs, reschedule Data Progression. Compression does not run with an on-demand Data Progression.
When compressed data is read, it is temporarily uncompressed in memory until the read is complete. When compression is disabled, pages
are permanently uncompressed during the next compression cycle, and the original compressed page is deleted as time and resources
permit. When a volume is deleted or a snapshot is coalesced, the related compressed data is also deleted.
Deleted data might create gaps in the compressed page, which can be lled with new compressed data. In addition, compressed pages are
defragmented during Data Progression to remove gaps and use space more eciently.
The Compression Savings amount is determined by comparing the total amount of space saved from all compressed pages to the total
amount of used space that is eligible for compression. For example, if compression saves 1 GB on a volume with 10 GB of used space that is
eligible for compression, the amount saved is 10 percent.
Apply Data Compression to a Volume
Apply Data Compression to a volume to reduce disk space usage for that volume.
1 If you are connected to a Data Collector, select a Storage Center from the drop-down list in the left navigation pane.
2
From the STORAGE menu, select Volumes.
The Volumes view is displayed.
3 On the Volumes view, select the volume you want to modify.
4 Click (Edit).
The Edit Volume dialog box opens.
5 Expand Data Reduction.
6 From the Data Reduction Prole drop-down list, select Compression.
7 Click OK.
Related links
Creating Volumes
Modifying Volumes
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Storage Center Administration