James D. Stallardblog

Recently, my Lacie Ethernet Disk (perhaps the cheapest server based storage money can buy) has been shutting down spontaneously. There was no fixed time or set of curcumstances and nothing in the logs other than the usual "shutdown at blah was unexpected" messages in the event logs. Sometimes it would stay up for a week, sometime not even 20 minutes.

The problem turned out to be the weather and was solved by moving it from the top of the rack to the middle.
Confused? Here goes...

The Lacie is not a particularly robust bit of kit internally, and the large disks generate a fair bit of heat. This is probably why the casing is metal as aluminium is an excellent conductor of heat, where plastic isn't. Overly high internal temperatures in the Lacie cause it to power off. My Lacie was sat in the top of my rack, the rest of the space being taken up by servers and the like.

My server room used to get very hot in summer, but last year I put in AirCon and things have much improved - but the unit is only 7Kw capable and the heat is not entirely dissipated from the rear of the rack due to lousy air circulation. The big servers are full of fans and cope fine, but the Lacie is a little more sensitive.

So, it turns out that when we have a bit of sun; as recently, the rack gets just hot enough internally to cause the Lacie to shutdown. I moved the Lacie to the middle of the rack where there is less heat and also where the ambient room temperature is lower and voila, it's been up for a while now and no issues.

Bulimia is not funny, but it was nevertheless entertaining watching BBC news this morning where John Prescott's bulimia was reported. Not even the usually straight-faced early morning presenters were able to keep the smile out of their faces and voices at the thought of the ex-deputy prime minister barfing his chinese dinner into westminster's porcelain chariots.

Desktop Virtualisation is the replacement of the traditional desktop hardware with a thin or zero client device that presents only an interface to a Virtual Machine - running on VMWare ESX/VI3/Virtual Server, Microsoft Virtual Server or some other virtualisation platform (seriously, there are others ). You can do this with a PC and a software application, but although useful in a number of situations, that's not what's got me interested.

My experience is currently limited to the Pano Logic Pano Device and Pano Desktop Manager Software v1.1 and later, but I'm voraciously reading whatever I can find about their competitors. Pano is not the only way to skin this particular cat and the industry hasn't yet sorted out the winners and losers in the marketplace.

The Pano device itself is basically an X-Windows terminal that connects to the X Server running on the Pano Desktop Manager (DM). The DM is running Centos and some clever software that allows the Pano devices to be attributed to a pool of Virtual Machines hosted on (in this case) a VMWare Virtual Infrastucture running ESX v3.5. The Pano device is able to find the DM via one of a number of methods, but my favourite is by configuring a special option on the DHCP servers. Once found, the DM registers the device and allows you to 'manage' it from a web application.

When a user powers on the pano device, they are presented (almost instantly) with a customisable X-Windows logon, which accepts their Active Directory domain credentials. The DM then proxies these credentials to a "vacant" Desktop Virtual Machine (DVM) and logs them in to the terminal services connection provided with Windows 2000svr, XP, 2003, Vista and 2008. All the standard applications are available that were installed when the VM was built/cloned, and the user notices nothing different from then on. There is some necessary configuration to do with the Active Directory in terms of GPOs, redirected folders and the like to ensure a smooth and integrated user experience, but essentially that's your lot.

So simple, It's a wonder we weren't doing it years ago.