The ramblings of a computer geek
Whilst building a new home machine I came across this issue where the third screen in my three screen setup was only seen as an “Unknown Display”. My machine has an on-board graphics card and a 2 port PCI-E riser graphics card, the monitors connected to the 2 port riser were working correctly, and the … Read more
If you need to SSH to a host but don’t have direct SSH access, you can perform a reverse SSH tunnel. For this you need a host that will except inbound connections to work as a “jump host”, it is possible without it, where you could SSH back to your client computer; however for the … Read more
PROBLEM As part of a storage replacement programme, we had migrated all our VMs off the NFS datastore. When attempting to unmount the datastore from the host(s) we where given this error: Call “HostDatastoreSystem.RemoveDatastore” for object “datastoreSystem-122544” on vCenter Server “vcenterFQDN” failed. An unknown error has occurred. Checking the /var/log/vmkernel.log on the host we saw … Read more
PROBLEM As part of a storage replacement programme, we had migrated all our VMs off the NFS datastore. When attempting to unmount the datastore from the host(s) we where given this error: Call “HostDatastoreSystem.RemoveDatastore” for object “datastoreSystem-122544” on vCenter Server “vcenterFQDN” failed. An unknown error has occurred. Checking the /var/log/vmkernel.log on the host we saw … Read more
When attempting to migrate a VM from VMware ESXi 5.5. to ESXi 6.0 U1 you may experience problems, this does not affect all VMs only some and they are typically VMs that have been backed up using an external backup tool and make use of CBT (Change Block Tracking). A bug within ESX 5.5 or … Read more
The Raspberry Pi lacks a real time clock, which means that the time can drift, so much so that NTP fails to update the software clock because its skewed so much. To resolve this you can do the following: Add this to /etc/ntp.conf: tinker panic 0 That will cause ntpd to sync despite the large … Read more
When attempting to use the check_ldap plugin, I found that unsecured LDAP lookups on port 389/TCP worked fine, but attempting a secure lookup on 636 or using TLS failed. Attempting a check_ldap check normally worked fine (i.e. to port 389), but attempting an LDAPS or LDAP TLS check failed with the following error: The check_ldap … Read more
So looking for something to use your Raspberry Pi for? I had a Mk1 Raspberry Pi laying around and thought it might be good to set it up as a SSH gateway, so I could easily and securely access my home machines when out and about. These instructions assume you have a Raspberry Pi which … Read more
If you need to test connectivity between two VMKernel ports VMK’s you can use the following command: If you have seperate IP stacks for different types of VMkernel ports you need to add this stack name to the command too:
From time to time you need to run normal POTS telephone over structured cabling, the main issue is that in the UK the pin outs can be different from the rest of the world, so buying a BT plug to RJ45 cable doesn’t always work. Below is a diagram of the cabling pinouts required for … Read more