How to Use Space Reclamation In Legacy Mode on Busy Systems

SR Information:

Product / Software Version: Any DXi platform with 2.2 and later software.

Problem Description: Space reclamation in DXi 2.2 and later software can cause problems for busy systems and make it difficult to reclaim enough space fast enough to keep the system running normally.

Overview

In DXi 2.2 software and later versions, compaction does not run as part of the normal space reclamation process as it did pre-2.2 software. Instead, it only runs the compaction phase when the system gets to low space mode, which can cause problems for busy systems and make it difficult to reclaim enough space fast enough to keep the system running normally.

Background

In pre-2.2 software, space reclamation ran all four phases:

Compaction
Reconciliation
Deletion
Compaction

Starting in 2.2 software, space reclamation only runs the following two phases:

Reconciliation
Deletion

Once the system reaches low space mode (10% free space), space reclamation will include the compaction phases as well. In some cases, this is too late and the system can’t compact space fast enough to offset ingest, or the system slows down significantly as it processes a lot of data through space reclamation and compaction.

This has been identified by Engineering as a problem and in they plan to modify space reclamation in a future 2.4 software version so that compaction is run much sooner than the low space threshold, alleviating these issues.