Why is there a mismatch between CLI and OSM for cluster aggregate capacity
Applies to
- ONTAP System Manager 9.6+ (OSM) New Experience
- Aggregate capacity
Questions
- Why is there a mismatch between CLI and System Manager for cluster and aggregate capacity?
- Why does System Manager dashboard report less available space than expected compared to CLI?
Answer
- The issue is visible when deduplication and compression are present
- The used capacity is all the logical space that is used
- The available space is physical space
- Deduplication and compression of the physical space that is left cannot be calculated
Logical Space
- Logical space refers to how theoretical space may be used without taking into account things like deduplication or compression
- Compression reduces the amount of physical storage required for a volume by combining data blocks in compression groups, each of which is stored as a single block
- Data deduplication is a process that eliminates excessive copies of data and significantly decreases storage capacity requirements
Physical space
- Physical space refers to how many physical blocks are being used in data aggregates. This does not include:
- Root aggregates
- Spare disks
- Parity disks
CLI output:
- You can review more information with the following commands:
::> storage aggregate show
::> aggr show-space
::> aggr show -fields physical-used,data-compaction-space-saved-percent,sis-space-saved-percent,composite-capacity-tier-used,size,physical-used-percent,data-compaction-space-saved,sis-space-saved