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Showing posts from 2012

Buying the right NAS device for your home lab.

Buying the right NAS device for a vSphere home lab is not an easy task. This blog post documents the decision process you should go through IMHO.

First, decide which data you are going to put on it. Lots of people buy a NAS for secondary data only (I.e. backups), but in a home lab, there's probably primary data too. How important is the data, and do you require a backup of this primary data?

Then, think about the volume of data you need. Is it 1TB, more like 5TB, or rather 10TB?

Number three, protection level. No one wants to lose data, but how badly? Surviving one disk failure is a minimum, but a RAID5 set enters its "danger zone" when that happens. That means an additional failure will make you lose all the data on the set. The danger zone ends after you've replaced the failed disk and it's contents have been rebuilt. RAID6 enters the danger zone after losing a second device before the first is rebuilt. Know your danger zone!

A fourth decision is speed. Bandwid…

Boot device priority in a vSphere VM

While playing around with the bios.bootDeviceClasses parameter (as shown in this example ), we found out that

a device not specified in allow: would still be used if all "allow:"ed devices are unusable (no CD connected, no PXE server found, etc.)a device specified in deny: would still be used if all other devices are unusable. So contrary to what the documentation suggests, "allow:" will just move certain devices to the front of the boot device list, and "deny:" moves those devices to the end of the list.
Hope this can help other people trying to make sense of setting boot order in a VM to achieve a specific behavior. In our case: get a VM to reliably boot from CD for automated deployment using the SDK.