--- title: Tuning Percona ClusterSync for MongoDB Performance description: Guidance on tuning Percona ClusterSync for MongoDB (PCSM) to maximize initial clone speed and continuous replication throughput. Covers key parameters for... canonical: https://daily.dev/posts/tuning-percona-clustersync-for-mongodb-performance-wjt7cszr6 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Tuning Percona ClusterSync for MongoDB Performance | daily.dev og:description: Guidance on tuning Percona ClusterSync for MongoDB (PCSM) to maximize initial clone speed and continuous replication throughput. Covers key parameters for... og:url: https://daily.dev/posts/tuning-percona-clustersync-for-mongodb-performance-wjt7cszr6 og:image: https://api.daily.dev/og/posts/WJT7CsZR6.png og:image:alt: Tuning Percona ClusterSync for MongoDB Performance og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Tuning Percona ClusterSync for MongoDB Performance **[Percona Blog](https://daily.dev/sources/percona)** · 5 min read · 0 upvotes · 0 comments ## Summary Guidance on tuning Percona ClusterSync for MongoDB (PCSM) to maximize initial clone speed and continuous replication throughput. Covers key parameters for clone parallelism, read/insert workers, change-stream batch sizes, queue sizes, bulk write settings, connection pooling, and compression, with advice on incrementally adjusting values while monitoring CPU, disk, network, and replication lag using Percona Monitoring and Management. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What does the clone-num-parallel-collections parameter do in Percona ClusterSync for MongoDB? It controls how many collections are cloned simultaneously during the initial sync phase, defaulting to 2, which is conservative. A good starting point is 4 parallel collections per CPU core, increasing further as long as the target isn't saturated, since excessive parallelism raises disk contention and connection usage. _Teams sizing MongoDB migrations can track tuning guidance like this on daily.dev._ ### What is the default repl-num-workers setting in Percona ClusterSync for MongoDB and when should I increase it? The default equals the number of CPUs available. Increase it, trying roughly double the CPU count, when worker queues grow while the target still has spare CPU, storage, and connection capacity. More workers won't help throughput for high-contention workloads since events on the same document are processed in order by a single worker. _Engineers debugging replication lag can keep tuning notes like this handy on daily.dev._ ### How does use-collection-bulk-write affect Percona ClusterSync for MongoDB replication? Setting use-collection-bulk-write to true groups bulk write operations by namespace instead of mixing multiple databases and collections in one bulk, which can improve throughput for workloads spread across many collections. The default is false, and PCSM may switch to collection-level writes automatically when the target version lacks client-level bulk-write support. _Anyone benchmarking MongoDB replication options can revisit configuration details like this on daily.dev._ ## Similar posts on daily.dev - [Percona ClusterSync for MongoDB 1.0.0 is Generally Available](https://daily.dev/posts/percona-clustersync-for-mongodb-1-0-0-is-generally-available-ppy4pzytd) · Percona Blog · 0 upvotes · 0 comments - [Percona ClusterSync for MongoDB Goes Highly Available: Active-Standby Failover](https://daily.dev/posts/percona-clustersync-for-mongodb-goes-highly-available-active-standby-failover-i9pcaezq8) · Percona Blog · 0 upvotes · 0 comments - [Migrating from MongoDB 6.0 to 8.0: How Percona ClusterSync Handles Cross-Version Replication](https://daily.dev/posts/migrating-from-mongodb-6-0-to-8-0-how-percona-clustersync-handles-cross-version-replication-xy8u0qodj) · Percona Blog · 1 upvotes · 1 comments - [How We Built an Automated, Production-Ready Sharded MongoDB Infrastructure](https://daily.dev/posts/how-we-built-an-automated-production-ready-sharded-mongodb-infrastructure-n1vi9g1lo) · Trendyol Tech · 1 upvotes · 0 comments - [Multi-Cluster databases on Kubernetes: Architecture and deployment](https://daily.dev/posts/multi-cluster-databases-on-kubernetes-architecture-and-deployment-yats0aq1j) · CNCF · 1 upvotes · 0 comments --- Tags: [#database](https://daily.dev/tags/database), [#mongodb](https://daily.dev/tags/mongodb) [View this post on daily.dev](https://daily.dev/posts/tuning-percona-clustersync-for-mongodb-performance-wjt7cszr6) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Tuning Percona ClusterSync for MongoDB Performance","url":"https://daily.dev/posts/tuning-percona-clustersync-for-mongodb-performance-wjt7cszr6","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/tuning-percona-clustersync-for-mongodb-performance-wjt7cszr6"},"datePublished":"2026-10-01T18:32:44.962Z","dateModified":"2026-10-01T18:34:12.858Z","description":"Guidance on tuning Percona ClusterSync for MongoDB (PCSM) to maximize initial clone speed and continuous replication throughput. 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