ESXi host upgrades via vSphere Update Manager (VUM, now Lifecycle Manager in newer versions) are routine operations that usually go smoothly. When they don’t, the failure modes can range from easily recoverable to genuinely painful. Here’s what I’ve encountered and how to handle it. Before You Start The things that should happen before any ESXi … Read more
VMFS (VMware File System) is a clustered filesystem that lets multiple ESXi hosts access the same LUN simultaneously. It’s reliable, well-tested, and handles concurrent access through distributed locking mechanisms. But VMFS corruption does happen — typically due to storage controller issues, firmware bugs, incorrect multipath configuration, or storage array problems — and knowing how to … Read more
NSX-V’s control plane runs on a cluster of controller VMs that manage logical network state — VXLAN mappings, logical router tables, and distributed firewall rule distribution. When controllers have problems, the symptoms are usually indirect and confusing: VMs can’t reach each other, logical networks stop working, or new VM deployments fail network connectivity. Here’s how … Read more
vCenter Single Sign-On (SSO) is the authentication backbone of the vSphere platform. It handles login to vCenter, manages identity sources, and issues tokens that vSphere services use to authenticate with each other internally. When it works, it’s invisible. When it breaks, everything breaks simultaneously and the error messages are spectacularly unhelpful. What SSO Actually Is … Read more
A failed vCenter upgrade is among the more stressful VMware events you’ll deal with. The VMs are still running, HA and DRS are still functioning on cached state, but vCenter itself is in an inconsistent state between versions and things are subtly broken in ways that compound over time. Here’s what to do. How Failed … Read more
Certificate issues in vSphere environments are the most reliable source of annoying, hard-to-diagnose problems I’ve encountered. They show up at upgrade time, after hardware changes, when adding new hosts, and sometimes apparently at random. Here’s what I’ve learned after dealing with these problems across multiple client environments. The VMCA and What It Does Starting with … Read more
The pool master is XenServer’s single management control plane for a resource pool. All XenCenter connections, all xe CLI commands that operate across the pool, all pool-level configuration changes — they all route through the pool master. Understanding what happens when it fails, and how to recover, is essential knowledge before you put XenServer into … Read more
Mail flow issues are the highest-urgency Exchange problem category — users notice immediately when email stops working, and everyone assumes it’s the mail server’s fault even when it’s not. A methodical approach saves time and prevents chasing the wrong thing. Start With Scope Before touching any configuration, establish the scope of the problem. Is the … Read more
Managed Availability is one of Exchange 2013’s most significant operational changes — and one of the least understood. It’s a built-in health monitoring and self-healing framework that watches Exchange components and takes corrective action when it detects problems. In theory, it means Exchange fixes itself. In practice, it can make troubleshooting significantly harder if you … Read more
At some point, you will open the Exchange Admin Center or EMS and find a database in a dismounted state. If you’re lucky, it’s a managed availability-triggered failover that resolved cleanly. If you’re not, you’re staring at a database that won’t mount because it’s in a dirty shutdown state. Here’s how to work through it … Read more