House of Brick Principal Architect
As database administrators, we are always searching for tools and technologies that can help us improve our lives, our jobs, our systems, and our processes. When a database server is virtualized, a whole new set of tools is available for database administrators to embrace. VMware vSphere 5.0 is the latest and greatest release from VMware, and House of Brick considers it the finest server platform in the world. The tooling and features included in this release allow for some of the greatest power and flexibility in the industry.
These core features allow DBAs more flexibility within the environment and, in practice, will help reduce downtime.
vMotion. vMotion allows for the migration of an in-use virtual machine from one physical server to another. If maintenance needs to be performed on a physical host, or if the host is overcommitted on resources and you need to move the virtual machine to a new host with less resource contention, it is as simple as a drag-and-drop and then two clicks. The VM stays up, the services all continue to work, and no downtime is experienced.
Storage vMotion. Storage vMotion gives the administrator the ability to migrate one or more virtual hard drives from one SAN LUN to another. This occurs transparently to the application. If a database administrator sees that a local drive is about to fill up, and that not enough free space on the LUN exists, the virtual disk can be relocated to a new LUN that has enough free space. At this point, the virtual disk can be grown and then the guest operating system can seamlessly extend the local partition. All of this can be done without downtime or hassle.
Snapshots. How many times have you had to develop, document, and test a minor upgrade roll-back plan? What if your fool-proof rollback plan could be as simple as three clicks? A snapshot is a point-in-time recovery point for a server. Take a snapshot with just a few clicks and the contents of the memory are stored. Any changes to the virtual hard drives are written to a delta disk. If something goes awry in the maintenance window, simply revert the VM to the state at when the snapshot was taken. Voilà – instant rollback! If the maintenance succeeded, simply commit the changes with two more clicks.
Storage I/O Control. If certain virtual machines are consuming substantially more storage resources than others and begin to negatively affect the performance of key virtual machines, a governor can be placed on the VM’s storage usage. It will let the administrator precisely limit a VM’s storage usage so that it does not affect any of its neighbors.
VMware Tools. Believe it or not, a component of the seemingly innocuous VMware Tools package should be considered one of the most important tools for database administrators. VMware Tools installs two new Perfmon Performance Objects along with their associated counters. These counters include:
Memory Active in MB
Memory Ballooned in MB
Memory Limit in MB
Memory Mapped in MB
Memory Overhead in MB
Memory Reservation in MB
Memory Shared in MB
Memory Shared Saved in MB
Memory Swapped in MB
Memory Used in MB
% Processor Time
Effective VM Speed in MHz
Host processor speed in MHz
Limit in MHz
Reservation in MHz
These counters should be collected with Perfmon and kept for historical purposes. If a user reports system performance problems, these stats can be analyzed and overlaid with vCenter statistics to determine if the host was under duress at the time of the reported problem. It can help rule out one layer in the stack and save time in troubleshooting.
vNUMA. vSphere 5 now extends the CPU NUMA to the virtual machine. A performance boost can be felt by properly aligning the virtual machine design with the NUMA structure in the physical host.
In addition to these core features, new product offerings from VMware can add even more features and tools into the DBA’s world.
vFabric Data Director. VMware’s new vFabric Data Director presents database-as-a-service databases for your internal cloud. The databases are self-contained, and provisioned in a self-service manner. It can reduce database sprawl while accelerating application development life-cycles.
vCloud Director. The pinnacle of VMware technology, vCloud Director, allows for an entire IT ecosystem to be rapidly provisioned in a self-service portal. Database and application servers can be deployed from a pre-built VM catalog quickly and seamlessly. The application development life-cycle is tremendously shortened by this self-service flexibility.
If you are interested in exploring these topics, they are covered more in depth here in the blog in the series of posts by Jim Hannan entitled vSphere 5 Advantages for VBCA.