This post describes the recovery of a broken virtual machine within ESXi 5.1 (update 1). The VM was damaged in several ways: the vmxf file was missing, and so was one of the vmdk files. The system was down and not bootable due to the missing files. In addition, the root password had been lost and needed recovery. The same procedure, or parts of it, should work for other ESXi VMs. The broken VM was running Red Hat, but that barely impacts the procedure, apart from the password recovery bit. Continue reading
After a security scan showed vulnerabilities, a recent client of mine requested the above update. The target server was a stand alone HP DL360 running ESXi version 5.0 (GA). The upgrade was performed with the following procedure, which should work equally as well for other ESXi versions. A system reboot is required. Continue reading
This post explains how to install the mlx4 driver into ESXi 5.1 in order that it can see and communicate with the NC542m 2-port Ethernet adapter card. The card was fairly new (at the time) and ESXi 5.1 could not see it by default. Continue reading
ESXi is popular hypervisor product from VMware. It comes with several management GUIs including Vsphere and VCenter. Command line tools are also bundled, though they are used more rarely. This article describes a short script to list all virtual machines on the system.
The script is below. It is intended to run under the Busybox shell, the default environment when you ssh directly into the system hosting ESXi. Continue reading
Solaris administrators may have seen the message “Catastrophic file error – zero length” in their system logs. Although it sounds serious, there is nothing “catastrophic” about it. This post explains how to stop the message from flooding your log files. Continue reading
This post shows how to use parallel processing to get a CPU intensive job done faster in Unix/Linux. By splitting a large task into several parts, it is quite easy to give each part to a separate CPU, and complete the task many times faster than it would on a single processor.
These days, even small PCs and other devices often come equipped with several CPU cores. But some tasks will use only one core, sometimes using 100% of it, while other cores stand by idle. Sometimes this is a waste of resources. Continue reading
This is a quick review of the Fedora 18 XFCE spin running on 64 bit intel, followed by a few post-install tips. Continue reading
How to find the memory on a Solaris system hosting primary and guest LDOMs
For capacity planning, it is useful to know how much free resource is available on a given LDOM server. That is, a “parent” system hosting several guest LDOMs. For example, if you want to know how many more LDOM’s the server could support. Continue reading
If the root password for a Unix system is lost or forgotten, it can be very difficult to regain root access and perform further administration work. Often it will be impossible. You could be lucky – there might be a user account with sudo access, or even a root shell still open on the system somewhere, for example on the system console. If the system is x86, you might be able to boot it from a live CD and restore root access by doctoring the root disk. Otherwise, with most systems (physical and virtual), it will often be a case of rebuilding the system from scratch.
Solaris is a bit different. It has long been possible with Solaris to regain root access by booting the physical system from a Solaris installation CD, mounting the original root disk and removing the root password string from the relevant file, usually /etc/shadow. The same technique works, surprisingly, with SPARC virtual systems, aka LDOMs. Proceed as follows. Continue reading
An LPAR, or logical partition, is an IBM virtual machine. LPARs run on a variety of IMB hardware and provide strong isolation between partitions. This article describes a method for quickly building LPARs running AIX on IBM pSeries hardware
AIX can be installed onto an LAPR using the distribution CDs (or rather, since this is a virtual machine, the ISO image files derived from those physical CDs). There are, however, two drawbacks with this:
- it does not include site specific customizations. If a piece of software like Apache or ssh is required on the LPAR, it must be installed separately – a pain if you have many LPARs to build.
- it is a slow process. AIX is supplied spread over several CDs. The administrator must swap CDs several times during the installation. This means hanging around and typing commands needed to mount and dismount the cd ISO images on the target LPAR, something that will have to be done several times during the installation.