Data Domain: How to Choose the Compression Type

Summary: This article explains the supported compression algorithms on Data Domain systems and provides guidance on selecting the appropriate compression type based on performance and data characteristics. ...

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Symptoms

Determine which compression type to use for a Data Domain filesystem.

Cause

Data Domain Operating System (DDOS) supports four compression algorithms with different compression ratios and CPU utilization:
Type Expected comp. CPU load
none 1x 0x
lz 2x 1x
gzfast 2.5x 2x
gz 3x 5x

Default Settings:

  • PowerEdge-based systems (For example: DD6400/DD6900/DD9900): gzfast
  • All other (Legacy) models: lz

Resolution

Compression Algorithm Details

  • gz offers the highest compression (approximately 3x) but consumes more CPU resources (about 5x compared to lz).
  • Compression results vary by data type:
    • For some data, gz may only be 10% better than lz.
    • For others, gz can be twice as effective.

Data Characteristics

  • Files with repetitive strings (such as, database files, log files) compress better with gz.

Performance Impact of gz

  • Backups: Initial full backups may run at ~50% of peak throughput due to higher CPU usage.
  • Cleaning: It takes longer because data is uncompressed and recompressed, potentially slowing backups and replication
  • Replication: Source system compresses data using the destination’s algorithm. If the destination uses gz, replication may slow down and impact other activities.

Recommended Use Cases for gz.

  • Applications with:
    • High deduplication
    • Low data churn
    • Minimal backup performance requirements
      Example: Nearline storage applications

Changing Compression Type

Important:

  • The filesystem must be disabled before changing the compression type.
  • New writes use the new compression type, when a change is made.
  • Existing data is converted during cleaning, which may increase cleaning time.
  • Monitor system performance for 1–2 weeks after the change.

To change the compression type:

# filesys disable
# filesys option set local-compression-type {none | lz | gzfast | gz}
# filesys enable

Affected Products

Data Domain

Products

Data Domain
Article Properties
Article Number: 000028820
Article Type: Solution
Last Modified: 07 Jan 2026
Version:  4
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