With so many features in VMware vSphere 5 relying on vCenter Server, its availability is more critical than ever....
Some IT pros expect VMware to improve vCenter architecture to address their concerns.
VMware products that rely on vCenter include vSwitches, the vShield security suite, VMware View, Site Recovery Manager, vCenter Operations, vCloud and more.
“People are starting to pay attention to vCenter a little more due to the criticality of it,” said Charles Gautreaux, a senior engineer at a large financial services company. “If that thing goes down, I can’t provision desktops, I can’t do my backups or manage my environment, manage my storage, even, in some cases.”
VMware vCenter Server’s criticality is especially acute when it comes to virtual desktops, according to Julian Wood, an independent IT consultant who works with various companies in the U.K.
“Many VDI environments require a connection through vCenter to see whether a machine is up, or to see whether it can pass information through vCenter to the virtual machine,” he said. “That means if vCenter is down, you can quite easily lose all your connectivity to a VDI environment, and that could impact thousands of your clients, and that is a big issue.”
Wood said he has seen at least one client replace VMware with Citrix XenServer after a vCenter Server outage. “That’s definitely license dollars that have moved from VMware to somebody like Citrix just for this reason,” he said.
But IT pros suspect that VMware will make vCenter more highly available and distributed.
“[VCenter Server] hasn’t really been designed from the ground up to be highly available, which is really what you need,” said Michael Webster, a VMware Certified Design Expert and director of IT Solutions 2000 Ltd., a VMware consultancy based in Auckland, New Zealand.
A VMware spokesperson did not confirm improvements to vCenter availability but said in an email, “We are constantly listening to our customers as we look at the development of our products.”
Improving vCenter availability
Today, users can deploy VMware’s vCenter Heartbeat for active-passive two-way clustering that provides failover in the event of an outage. Gautreaux said the Heartbeat feature is only a temporary measure though.
Running vCenter Server in a virtual machine (VM) also offers protection options that come with vSphere, such as VMware High Availability. Also, while certain management products require vCenter to run, a vCenter Server outage will not take down production VMs.
Users can also see all the ESXi hosts being managed through multiple vCenter Server instances in one interface through a feature called Linked Mode. But if multiple vCenter Servers run in the environment managing multiple ESXi clusters, one cannot take over for another in the event of an outage. Each manages its own portion of the environment and must be protected separately.
Linked Mode is also “not the answer,” according to Maish Saidel-Keesing, a virtualization administrator for an Israeli technology company. He said it is a “patch to introduce scale, but not a real solution, because you could not provide redundancy between them. They will need an active-active model, which is something that does not exist today.”
There were some rumblings at VMworld Europe last fall about the possibility of database intellectual property from the vFabric suite being ported into the vCenter Server architecture. It was unclear exactly which member of the vFabric product line was being considered, but possible candidates are the in-memory database GemFire or SQLFire, a version of GemFire with a SQL interface.
An in-memory database set up between multiple vCenter Servers could pave the way for federation, in which any vCenter instance in an environment could manage any host, and to have that change on the fly if one vCenter instance goes offline.
“Architecturally it’s still a bit of a fudge to try and do replication of that Virtual Center database, so I would hope that VMware is looking carefully at this,” said Wood. “They’ve got amazing technology in some of the other products in the vFabric suite which are massively scalable, highly available databases, so hopefully some of that technology will work its way towards Virtual Center.”
Some users want to see the Windows back end for vCenter Server disappear entirely in favor of Linux, which they consider more reliable.
Meanwhile, VMware has begun to make strides in this area with the release of the Linux-based vCenter Server Appliance. So far, the appliance offers limited functionality.
VMware documentation on vCenter Server Appliance says it doesn’t support IPv6, Linked Mode, SQL Server or DB2 databases. Some users also report that plug-ins developed for the Windows-based vCenter by storage, networking and backup providers also haven’t been ported over to work with the vCenter Server Appliance yet. Others point out that the cross-platform vSphere Web Client used with the vCenter Server Appliance has yet to add all the functionality of the Windows-based vSphere Client.
Beth Pariseau is a senior news writer for SearchServerVirtualization.com. Write to her at firstname.lastname@example.org.