Symptoms

A Unity storage pool has entered a degraded state, displaying a "Faulted/Attention" message, due to excessive pool consumption. The automatic snapshot deletion feature has paused because there are not enough eligible snapshots to delete, preventing the pool from reaching the high threshold. To resolve this issue, follow the suggestions below. 

Cause

To ensure optimal pool performance, verify that the pool has sufficient capacity and available space, and that subscriptions are within normal limits. When a pool approaches maximum capacity, the automatic snapshot deletion feature (also known as Auto-Harvest) is triggered, deleting snapshots to reclaim space. If you encounter the message "Warning: Automatic snapshot deletion paused, as an expected event" it indicates that the feature has paused as designed. The autodeletion process resumes when pool usage reaches the designated thresholds, at which point the Auto-Harvest process automatically deletes snapshots to free up space.

Resolution

Configuring automatic deletion: Snapshot Expiration: Enable automatic deletion for a snapshot when creating it by setting an expiration date.Pool Thresholds: Define the pool consumption thresholds that trigger the automatic deletion process in the pool configuration settings.UEMCLI: Use UEMCLI to configure the -poolFullPolicy for individual file systems. Specifies the policy to follow when the pool is full and a write to the file system is tried. This attribute enables you to preserve snapshots on the file system when a pool is full. Valid values are: deleteAllSnaps—Delete snapshots that are associated with the file system when the pool reaches full capacity. failWrites—Fail write operations to the file system when the pool reaches full capacity. Enable automatic snapshot deletion for a pool: Under STORAGE, select Pools. Select the relevant pool and click the Edit icon.Select the Snapshot Settings tab.In the Automatically delete oldest snapshots section, select whether you want the automatic deletion to occur when the total pool consumption space reaches a threshold you set, snapshot pool consumption space reaches a threshold you set, or both. For each option, you can also set the threshold when the automatic snapshot deletion stops. Monitor pool space allocation and usage: Under STORAGE, select Pools. Select the relevant pool, and then select the Edit icon. Select Usage > Capacity to view pool space usage with metrics on: current pool capacity, space used, alert threshold, data reduction savings, and a graph showing the pool's used capacity over time. Note the following: The Non-base Space field displays the space used by all snapshots and thin clones in the pool. The Used field displays the percentage of the pool's total space that has been reserved by its associated storage resources. This total includes the space used by thin clones and snapshots. When this value is over 100%, the pool is oversubscribed. The Preallocated Space displays the amount of remaining space in the pool that is reserved for, but not actively being used by, a storage resource. The Alert Threshold field displays the percentage of storage allocation at which Unisphere generates notifications about the amount of space remaining in the pool. You can set this value between 50% and 84%. Select Storage Resources to view a list of storage resources in the pool, along with the following metrics: total amount of pool space used by each resource and amount of pool space used for each resource's snapshots and thin clones.

Support Cases