{"id":4295,"date":"2026-05-15T15:34:42","date_gmt":"2026-05-15T15:34:42","guid":{"rendered":"https:\/\/cloudobjectivity.co.uk\/?p=4295"},"modified":"2026-05-17T15:35:51","modified_gmt":"2026-05-17T15:35:51","slug":"expand-shared-vmdks-with-clustered-applications-in-vmware-vsan-for-vcf-9-1","status":"publish","type":"post","link":"https:\/\/cloudobjectivity.co.uk\/index.php\/2026\/05\/15\/expand-shared-vmdks-with-clustered-applications-in-vmware-vsan-for-vcf-9-1\/","title":{"rendered":"Expand Shared VMDKs with Clustered Applications in VMware vSAN for VCF 9.1"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"4295\" class=\"elementor elementor-4295\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-75f55c29 e-flex e-con-boxed e-con e-parent\" data-id=\"75f55c29\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-21ef2e15 elementor-widget elementor-widget-text-editor\" data-id=\"21ef2e15\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t\n<p class=\"wp-block-paragraph\">Published on May 15, 2026.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>Executive Overview<\/strong><\/p>\n\n<p class=\"wp-block-paragraph\">Running business-critical, clustered enterprise software (such as Microsoft Windows Server Failover Clustering or Oracle RAC) on a virtualized platform has traditionally required rigid, complex storage configurations. Historically, to allow multiple virtual machines to share a single virtual disk (VMDK), administrators had to utilize SCSI-3 Persistent Reservations over dedicated physical fabrics or engage in strict Multi-Writer locks.<\/p>\n\n<p class=\"wp-block-paragraph\">A major operational limitation of these shared architectures was the inability to expand the size of the shared disk on-the-fly; modifying capacity required taking the entire cluster offline, disrupting application availability. In VMware Cloud Foundation (VCF) 9.1, Broadcom natively resolves this infrastructure bottleneck by introducing <strong>Online Expansion of Shared VMDKs<\/strong>, allowing live storage scale-outs without application or cluster downtime.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>Features<\/strong><\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Dynamic Online SCSI-3 PR Volume Resizing:<\/strong> Modifies the underlying storage allocation blocks for disk files actively locked by multi-node guest operating system clusters while I\/O operations are executing.<\/li>\n\n<li><strong>Integrated Clustered VMDK Lock-Stepping:<\/strong> Hypervisor-level communication layers that pass metadata changes safely across all ESXi hosts participating in the shared application ring, preventing file table corruption.<\/li>\n\n<li><strong>vSAN Express Storage Architecture (ESA) Data Fabric Optimization:<\/strong> Leverages the log-structured write mechanics of the ESA architecture to write data into expanded blocks without requiring mirror re-balancing during the change.<\/li>\n\n<li><strong>UI and API Orchestration Uniformity:<\/strong> Extends standard vSphere Client &#8220;Edit Settings&#8221; slider control and programmatic REST API structures to shared disks, matching the operational experience of single-user VMDKs.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\"><strong>Benefits<\/strong><\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Elimination of Tier-1 Application Maintenance Windows:<\/strong> Database and infrastructure teams can instantly resolve emergency disk space shortages for critical applications during peak hours without orchestrating high-risk cluster reboots.<\/li>\n\n<li><strong>SLA Compliance and Continuous Uptime:<\/strong> Keeps clustered enterprise services online, preventing secondary failover events or unexpected application timeouts during storage changes.<\/li>\n\n<li><strong>Simplified Storage Operations:<\/strong> Erases the need for engineers to configure complex target mappings or auxiliary helper utilities to manage multi-host storage volumes.<\/li>\n\n<li><strong>Hardware Sizing Precision:<\/strong> Allows organizations to safely adopt a &#8220;just-in-time&#8221; thin-provisioning storage model for databases, expanding disks only when necessary instead of over-provisioning expensive NVMe arrays upfront.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\"><strong>Use Cases<\/strong><\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Scaling High-Availability SQL Server \/ Oracle Estates:<\/strong> Scaling up the active storage layout for multi-terabyte transactional database instances experiencing sudden transaction log volume surges.<\/li>\n\n<li><strong>Enterprise ERP Failover Clusters:<\/strong> Dynamically expanding shared system volumes supporting core operational planning engines without pausing production shifts.<\/li>\n\n<li><strong>Legacy App Modernization via VCF:<\/strong> Transitioning older clustered bare-metal workloads seamlessly onto VCF 9.1 software-defined layers without rewriting guest OS configurations.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\"><strong>Alternatives<\/strong><\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Offline Shared Disk Resizing (Legacy vSAN \/ Competitor Stacks):<\/strong> Powering down the client node workloads, removing the multi-writer flags, expanding the volume size, re-attaching the configuration parameters, and cold-booting the application cluster. While safe, this breaks availability metrics and demands off-hours administrative staff allocations.<\/li>\n\n<li><strong>In-Guest Software-Defined Storage Overlays:<\/strong> Utilizing guest-level software utilities (such as raw network block devices or network file shares) to stitch independent virtual disks together. This shifts the operational tax inside the virtual machine, increases CPU overhead, and fragments storage visibility.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\"><strong>Alternative Perspective<\/strong><\/p>\n\n<p class=\"wp-block-paragraph\">While hot-expanding a shared disk is a significant day-two operational enhancement, it introduces a dangerous point of failure at the guest operating system level. The hypervisor can seamlessly scale the underlying virtual volume block layout, but the guest OS (e.g., Windows Disk Management or Linux LVM) must still successfully resize its internal partition file system under active load. If the guest OS kernel experiences an internal locking panic during its volume scan, the application layer can still crash\u2014meaning that while <em>infrastructure<\/em> downtime is designed out, <em>application-level<\/em> verification risks remain.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>Final Thoughts<\/strong><\/p>\n\n<p class=\"wp-block-paragraph\">The inclusion of online shared VMDK expansion in VCF 9.1 removes one of the final remaining functional advantages held by legacy, external fiber-channel storage arrays. By making shared application volumes behave with the same flexibility as simple dev-test disks, Broadcom cements vSAN ESA as a highly practical storage tier for mission-critical core architectures.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>Source<\/strong><\/p>\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/blogs.vmware.com\/cloud-foundation\/2026\/05\/15\/expand-shared-vmdks-in-vmware-vsan-for-vcf-9-1\/\" target=\"_blank\" rel=\"noreferrer noopener\">Expand Shared VMDKs with Clustered Applications in VMware vSAN for VCF 9.1<\/a> (Published: May 15, 2026)<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>Published on May 15, 2026. Executive Overview Running business-critical, clustered enterprise software (such as Microsoft Windows Server Failover Clustering or Oracle RAC) on a virtualized platform has traditionally required rigid, complex storage configurations. Historically, to allow multiple virtual machines to share a single virtual disk (VMDK), administrators had to utilize SCSI-3 Persistent Reservations over dedicated [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"elementor_theme","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[25,31,53,52],"class_list":["post-4295","post","type-post","status-publish","format-standard","hentry","category-vmware-news","tag-ai","tag-oracle","tag-vcf","tag-vmware"],"_links":{"self":[{"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/posts\/4295","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=4295"}],"version-history":[{"count":4,"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/posts\/4295\/revisions"}],"predecessor-version":[{"id":4302,"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/posts\/4295\/revisions\/4302"}],"wp:attachment":[{"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=4295"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/categories?post=4295"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cloudobjectivity.co.uk\/index.php\/wp-json\/wp\/v2\/tags?post=4295"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}