Administrator Guide

5. Click Edit Advanced Volume Settings.
The Edit Advanced Volume Settings dialog box opens.
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.
Supported Hardware Platforms
The following controller series support Data Reduction:
• SCv3000 Series (Supports Compression only)
• SC4020
• SC5020
• SC5020F
• SC7020
• SC7020F
• SC8000
• SC9000
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 eciently.
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. Select a Storage Center from the Storage view. (Data Collector connected Storage Manager Client only)
2. Click the Storage tab.
3. In the Storage tab navigation pane, select a volume.
4. In the right pane, click Edit Settings. The Edit Volume dialog box opens.
5. From the Data Reduction Prole drop-down list, select Compression.
6. Click OK.
Related link
Creating Volumes
Modifying Volumes
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Storage Center Administration