Data Domain: Filesystem Space Utilization Alerts

Summary: This article provides information about Data Domain (DD) Space alerts, such as when and why they occur.

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Instructions

All Data Domain Restorers (DDRs) contain a pool or area of storage known as the 'Active Tier' or 'Cloud Tier':
  • The Active Tier is where newly ingested files or data resides. On most DDRs, files remain here until expired or deleted by a client backup application.
  • On DDRs configured with Extended Retention (ER) or Long Term Retention (LTR) the data movement process may run periodically to migrate old files from the active tier to archive or cloud tiers.
  • The only way in which to reclaim space in the active tier which is used by deleted or migrated files is by running the garbage collection/clean process (GC).

The current utilization of the active tier can be displayed using the filesys show space or df commands:

# df
Active Tier:
Resource           Size GiB   Used GiB   Avail GiB   Use%   Cleanable GiB*
----------------   --------   --------   ---------   ----   --------------
/data: pre-comp           -    33098.9           -      -                -
/data: post-comp    65460.3      518.7     64941.6     1%              0.0
/ddvar                 29.5       19.7         8.3    70%                -
/ddvar/core            31.5        0.2        29.7     1%                -
----------------   --------   --------   ---------   ----   --------------
Note: If configured, the details of the archive or cloud tiers are shown below the active tier.
 
 

DD Space Usage alert information:

  • A Data Domain system has an internal design where it automatically generates an alert when the active tier space utilization reaches 90%.
  • This alert configuration can be changed.
    • By default, the warning-space-usage value is set to 90% and the critical-space-usage value is set to 95%.
    • The current values of the warning-space-usage and critical-space-usage parameters can be checked using the following commands:
      (Roles required: admin, limited-admin, user, backup-operator, security, none.)
    # filesys option show warning-space-usage
    # filesys option show critical-space-usage
  • To set the values of the warning-space-usage and critical-space-usage parameters:
    (Roles required: admin, limited-admin.)
# filesys option set warning-space-usage <space-usage-value>

(Where the range of <space-usage-value> is 50 - 90.)

# filesys option set critical-space-usage <space-usage-value>

(Where the range of <space-usage-value> is 75 - 98.)

Note: It is recommended that the warning-space-usage percentage is set lower than the critical-space-usage percentage.
 
 

Alert examples:

  • Alerts or messages such as the following can be displayed when the active tier starts to run out of available space:
    • EVT-SPACE-00004: Space usage in Data Collection has exceeded 90% threshold:
      • This is the initial alert that occurs when the DD space is 90% consumed.
      • No processes are impacted.
    • EVT-SPACE-00004: Space usage in Data Collection has exceeded 95% threshold:
      • This alert occurs when the DD space-utilization has reached 95%.
      • The performance may get impacted like cleaning and other processes.
    • EVT-SPACE-00004: Space usage in Data Collection has exceeded 100% threshold:
      • If the active tier becomes 100% full, no new data can be written to the DDR.
      • This may cause backups and replication processes to fail. In this scenario, log messages such as the following may be displayed: 
        CRITICAL: MSG-CM-00002: /../vpart:/vol1/col1/cp1/cset: Container set [container set ID] out of space

        CRITICAL: MSG-CM-00002: /../vpart:/cloud1/col1/cp1/cset: Container set [container set ID] out of space

        MSG-INTRNL-00001: PANIC: ddr/segstore/ss_nvram.c: ssnv_cp_append: 1887: Failed in cp_append_container: Err = [Storage has reached the configured maximum size

 

Notes:
  • When the cloud capacity is full, the cloud cset gets full, and when cloud data-movement is running, there will not be any new containers written to the cloud cset causing a PANIC.
  • For Active tier, the Data Domain File System (DDFS) can become read-only when data is written above 100% usage.
  • It may also cause PANIC when NVRAM replay is run and no more containers can be written to the disks.
  • In some circumstances, the Active Tier or Cloud Tier becoming full may cause the Data Domain File System (DDFS) to become read-only, or cause PANIC, and it may be difficult to even bring up File System.
  • Both the Active Tier and the Cloud Tier are affected if DDFS panics. 
 

DDFS Utilization must be actively & carefully managed, otherwise the situation above may occur. 

 

Checklist for DD Capacity issues:

The details of these steps can be found in article: Data Domain: How to solve high space consumption or low available capacity on Data Domain Restorers (DDRs)

  • Step 1 - Determine whether an active tier clean must be run.
  • Step 2 - Check for large amounts of replication lag against source replication contexts
  • Step 3 - Check for mtrees which are no longer required
  • Step 4 - Check for old mtree snapshots
  • Step 5 - Check for old files on the system
  • Step 6 - Check for backups which include a large number of small files
  • Step 7 - Check for lower than expected de-duplication ratio
  • Step 8 - Check whether the system is a source for collection replication
  • Step 9 - Check whether data movement is being regularly run
  • Step 10 - Add additional storage to the active tier

Videos

   

Affected Products

Data Domain, DD OS 6.2
Article Properties
Article Number: 000019749
Article Type: How To
Last Modified: 08 Sept 2026
Version:  8
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