# galera Published articles for galera. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## How Linux Large Folios Can Amplify Disk Writes in PXC/Galera Workloads DevFeed: [How Linux Large Folios Can Amplify Disk Writes in PXC/Galera Workloads]() Original publisher: [Read original article]() Author: Przemysław Malkowski Published: 2026-10-16T12:58:08Z Content type: article Language: en Sources: [Percona]() Topics: [XtraDB Cluster (PXC)](), [Linux Kernel](), [XFS]() Tags: [galera](), [hardware-and-storage](), [insight-for-dbas](), [large-folios](), [mariadb](), [mmap](), [mysql](), [page-cache](), [uncategorized](), [xtradb-cluster-pxc]() ### AI overview An investigation into periodic disk-write bursts in a PXC/Galera cluster links the behavior to Linux large folios after an operating system upgrade. Galera's memory-mapped cache can trigger writeback of entire folios for small updates, amplifying disk writes. The article explains why InnoDB writes behaved differently and discusses diagnostic signals and possible workarounds. ### Source excerpt We've recently been dealing with an interesting customer case where a PXC version upgrade from 5.7 to 8.0 seemed to trigger a completely unexpected problem. Even though the workload and MySQL settings did not change, all PXC members began exhibiting sparse but regular bursts of massive disk writes. Yet the MySQL side workload statistics that ... Continued The post When a Small Change Writes Too Much - How A Linux Kernel Improvement Can Strike You in PXC/Galera Workloads appeared first on Percona. ## Your Galera cluster's hardest problem was never the replication library DevFeed: [Your Galera cluster's hardest problem was never the replication library]() Original publisher: [Read original article]() Author: Valeria Bogatyreva Published: 2026-10-08T16:07:52Z Content type: opinion Language: en Sources: [Percona]() Topics: [XtraDB Cluster (PXC)](), [site-reliability-engineering](), [Service fabric]() Tags: [concurrent](), [error](), [galera](), [mysql](), [percona](), [percona-announcements](), [production](), [replication](), [xtradb-cluster-pxc]() ### AI overview The article argues that production incidents in MySQL Galera Cluster are often difficult because diagnosing the cause takes longer than fixing it. It describes Percona MySQL Support for existing clusters and Percona XtraDB Cluster as options following the end of support for current MySQL Galera Cluster versions, emphasizing support, migration, and continued MySQL compatibility. ### Source excerpt Ask anyone who runs a multi-node MySQL Galera Cluster in production about their worst night. Almost nobody says write-set replication was wrong. They say something closer to this: "All queries piling up... no error messages in logs." Twenty minutes of downtime, ended only when a human picked a node to kill. (codership-team) Or the flow-control ... Continued The post Your Galera cluster's hardest problem was never the replication library appeared first on Percona. ## When pt-online-schema-change "where" Meets Galera: Understanding Chunk Auto-Resize and Flow Control DevFeed: [When pt-online-schema-change "where" Meets Galera: Understanding Chunk Auto-Resize and Flow Control]() Original publisher: [Read original article]() Author: Corrado Pandiani Published: 2026-09-28T13:56:53Z Content type: article Language: en Sources: [Percona]() Topics: [XtraDB Cluster (PXC)](), [downtime]() Tags: [downtime](), [flow](), [galera](), [insight-for-dbas](), [insight-for-developers](), [mysql](), [open-source](), [percona-software](), [percona-xtradb-cluster](), [pt-onine-schema-change](), [pxc](), [resize](), [toolkit](), [xtradb-cluster-pxc]() ### AI overview The article examines how pt-online-schema-change's adaptive chunk sizing can cause severe Galera Flow Control when a selective WHERE clause discards most rows during a copy. It describes a Percona XtraDB Cluster case and says the article proposes practical mitigations, though the supplied excerpt ends before those details. ### Source excerpt Percona Toolkit's pt-online-schema-change (pt-osc) has long been the preferred solution for performing online schema changes with minimal downtime. Its chunk-based copy algorithm is designed to adapt dynamically to the workload, making it suitable for very large tables in production environments. However, under specific conditions, one of its optimization mechanisms can become counterproductive. During a customer ... Continued The post When pt-online-schema-change "where" Meets Galera: Understanding Chunk Auto-Resize and Flow Control appeared first on Percona. ## Too many GCache Page Files in MySQL Data Directory DevFeed: [Too many GCache Page Files in MySQL Data Directory]() Original publisher: [Read original article]() Author: Kedar Vaijanapurkar Published: 2026-09-17T05:29:14Z Content type: tutorial Language: en Sources: [Percona]() Topics: [XtraDB Cluster (PXC)](), [Replication](), [Transactions](), [MySQL]() Tags: [cluster](), [database-administration](), [disk-space](), [galera](), [galera-replication](), [gcache](), [gcache-freeze-purge-at-seqno](), [gcache-keep-pages-count](), [gcache-page](), [gcache-page-files](), [gcache-purge](), [gcache-troubleshooting](), [mysql](), [mysql-disk-space](), [mysql-troubleshooting](), [percona-xtradb-cluster](), [pxc](), [replication](), [xtradb-cluster-pxc]() ### AI overview An investigation into thousands of GCache page files accumulating in a Percona XtraDB Cluster data directory. The article explains how frozen GCache purging caused disk growth, links the behavior to a cluster partition, and describes reproducing it by setting gcache.freeze_purge_at_seqno and generating workload. ### Source excerpt Learn why PXC accumulates thousands of gcache.page.* files, how frozen GCache purging causes disk growth, and how to safely recover and rejoin using IST. The post Too many GCache Page Files in MySQL Data Directory appeared first on Percona. ## Enabling TLS in PXC without Downtime DevFeed: [Enabling TLS in PXC without Downtime]() Original publisher: [Read original article]() Author: Juan Arruti Published: 2026-09-09T23:32:15Z Content type: tutorial Language: en Sources: [Percona]() Topics: [TLS (Transport Layer Security)](), [Replication](), [Security](), [Network](), [openssl]() Tags: [galera](), [high-availability](), [insight-for-dbas](), [mysql](), [open-source](), [percona](), [pxc](), [replication](), [security](), [ssl](), [tls](), [tls-handshake](), [uncategorized](), [xtradb-cluster-pxc]() ### AI overview This tutorial explains how to enable TLS for replication traffic in Percona XtraDB Cluster without a full cluster restart. Using Galera's socket.dynamic option, operators can perform two rolling restarts: first allowing encrypted and plaintext connections, then enforcing TLS-only communication. ### Source excerpt Starting with Percona XtraDB Cluster (PXC) 8.0, replication traffic encryption is enabled by default. That said, it's common to find clusters running without TLS that suddenly need it: a new compliance requirement, an audit finding, a network segment that is no longer considered trusted. PXC has a variable for exactly that case, pxc-encrypt-cluster-traffic, which handles ... Continued The post Enabling TLS in PXC without Downtime appeared first on Percona.