DefinIT Because if IT were easy, everyone would do it…

28Oct/12Off

Installing VMware vSphere Single Sign On (SSO) in Multi-site Mode

Posted by Sam McGeown

vmware logo VMware vSphere Single Sign On (SSO) can be installed in Multi-site mode to support local sign-on to vCenters that you want to be part of the same single sign on domain - for example, if you want to install Linked-Mode and have the advantage of a single pane of glass view, but can't risk using a single SSO instance across the WAN. In other words, from VMware's blog post:

Multisite deployments are  where a local replica is maintained at remote sites of the primary vCenter Single Sign-On instance. vCenter Servers are reconfigured to use the local vCenter Single Sign-On service and reduce authentication requests across the WAN. Multisite deployments do drop the support of single pane of glass views unless Linked Mode is utilized and multisite deployments are actually required to maintain Linked Mode configurations where roles, permissions and licenses are replicated between linked vCenter servers. Linked mode will re-enable single pane of glass views across multisite instances.

17Oct/12Off

DataStore conflicts with an existing DataStore in the DataCenter – Manually disabling Storage I/O Control

Posted by Sam McGeown

vmware logoI ran into this issue yesterday while reconnecting hosts in our vCenter Server following a complete reinstall - the reasons for which are a long story, but suffice to say that there were new certificates and the host passwords were encrypted with the old ones.

The LUNs had been unpresented at the hardware level by the storage team, but had not been unmounted or removed from vCenter. This is *not* the way to remove storage - let me re-iterate: remove storage properly. Unfortunately in this case the storage was removed badly - doing this can lead to a condition called "All Paths Down" or APD which is best explained by Cormac Hogan (@vmwarestorage) in the article Handling the All Paths Down (APD) condition.

5Oct/12Off

Host disk write latency errors – troubleshooting

Posted by Simon Eady

vmware logoSo recently we upgraded our cluster monitoring suite to it's latest iteration (Veeam ONE), it was not long before I began to receive emails from the monitor informing me of Host disk write latency "errors" (Datastore write latency had exceeded the defined threshold in the monitor) on several of the Datastores on our SAN.

Naturally I began the process of cross referencing backup routines and any heavy I/O routines that may have been running at the time the warning messages were generated. My conclusion was that even under average load these alerts were being generated, which was far from ideal even if we had not noticed any performance problems with any of the busy VMs.

After consulting the web/reference material and a few very knowledgable friends it was clear the first port of call was the Host Datastore Multipath policy. Upon quick inspection, all of the offending Datastores were configured with the Path Selection "Most Recently Used (vmware)". I had the option to set the Path Selection to "Round Robin (vmware)" but before doing so I double checked our MSA2312i SAN could support such a policy, which in this case it did.

4Oct/12Off

vCenter 5.1 – Configuring vCenter Linked Mode

Posted by Sam McGeown

One thing we have been meaning to do for a while but haven't got round to is getting our Virtual Center Servers into "Linked" mode - essentially to provide a single pane of glass view of our entire virtual estate. One vCenter resides on the other side of our DMZ and manages hosts isolated for security purposes. I've created an IPSec server-to-server connection and allowed that through the firewall to secure traffic between the DMZ VC and LAN VC.

For the purposes of this, let's call them DefinIT-VC01.definit.co.uk and DefinIT-VC02.definit.test.