priyeshkaratha commented on code in PR #8907: URL: https://github.com/apache/ozone/pull/8907#discussion_r2409356045
########## hadoop-hdds/docs/content/design/storage-distribution.md: ########## @@ -0,0 +1,180 @@ +--- +title: Storage Capacity Distribution Dashboard +summary: Proposal for introducing a comprehensive storage distribution dashboard in Recon. +date: 2025-08-05 +jira: HDDS-13177 +status: Under Review +author: Priyesh Karatha +--- + +<!-- + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, + either express or implied. See the License for the specific + language governing permissions and limitations under the License. +--> + +# Abstract + +Ozone currently lacks a unified interface to monitor and analyze storage distribution across its cluster components. This makes it difficult to: + +- Understand data distribution across the cluster +- Debug storage reclamation issues +- Monitor pending deletion progress +- Analyze utilization patterns +- Identify potential bottlenecks and imbalances + +This proposal introduces a comprehensive **Storage Capacity Distribution Dashboard** in Recon to address these challenges. + +--- + +# Key Features + +## 1. Storage Distribution Analysis + +Detailed breakdown of storage usage across components: + +- **Global Used Space**: Represents the actual physical storage consumed on the DataNodes. +- **Global Namespace Space**: Logical size of the namespace, calculated as the sum of pendingDirectorySize + pendingKeySize + totalOpenKeySize + totalCommittedSize, multiplied by the replication factor. +- **Open Keys and Open Files**: Space occupied by data in open keys and files that are not yet finalized. +- **Committed Keys**: Space used by fully committed key–value pairs. +- **Component-wise Distribution**: Breakdown of metrics across OM, SCM, and DataNodes. + +## 2. Deletion Progress Monitoring + +Track pending deletions at various stages: + +- **OM Pending Deletions**: Keys marked for deletion at OM +- **SCM Pending Deletions**: Container-level deletions managed by SCM +- **DataNode Pending Deletions**: Block-level deletion metrics on each DataNode + +## 3. Cluster Overview Metrics + +Summarized cluster statistics: + +- Total capacity and used space +- Free space distribution across components + +--- + +# Implementation Approaches + +## Approach 1: Recon-based Implementation + +Leverage the existing Recon service to build the dashboard with centralized and efficient data collection. +Recon currently maintains synchronization with the OM database and constructs the NSSummary tree, providing established calculation logic for metrics such as openKeysBytes and committedBytes. +Additionally, Recon already possesses a comprehensive physical and logical capacity breakdown through its OM DB insights component. + +### Benefits + +- **Unified Data Source**: All metrics aggregated centrally in Recon +- **Performance Optimization**: Incremental sync reduces the load +- **Reduced Overhead**: Avoids redundant calculations across services +- **Code Reusability**: Built on top of existing Recon infrastructure and endpoints + +### Component-wise Enhancements + +#### **DataNodes (DN)** + +- **Current State**: DNs expose storage metrics in their reports +- **Enhancement**: + - Add `pending deletion byte counters` in container metadata + - Calculate total pending per DN from container metadata and publish metrics +- **Responsibilities**: + - Report actual and pending deletion usage per container + +#### **Storage Container Manager (SCM)** + +- **Current Gap**: No block size tracking in the block deletion process +- **Enhancement**: + - Track block sizes when OM issues a deletion request + - Send a deletion command to DN along with block size and replication factor + + ``` + OM → SCM: block deletion request + block size + SCM → DN: delete command + block size + replication factor + ``` + +- **Responsibilities**: + - Serve as the metadata bridge between logical keys and physical blocks + +#### **Ozone Manager (OM)** + +- **Enhancement**: + - Compute block sizes during deletion +- **Responsibilities**: + - Expose logical storage metrics: committed keys, open keys, namespace usage + +#### **Recon** + +- **Enhancement**: + - Add a new dashboard aggregating: + - Logical metrics from OM + - Deletion progress from SCM + - Container-level metadata from DNs +- **Data Sources**: + - OM DB (via Insight Sync) + - SCM Client API + - DN BlockDeletingService metrics Review Comment: We are scrapping from jmx endpoint for each DN BlockDeletingService metrics. -- This is an automated message from the Apache Git Service. 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