ESXi 5.5 enable SSD

VMware’s ESXi servers frequently are unable to recognize attached SSD devices, especially when they are behind a RAID controller. If a storage device is not recognized as an SSD, it cannot be designated for vFRC or the Virtual Flash Host Swap Cache function. A set of commands outlined in VMware’s KB 2013188 will mark the storage device as a local SSD and enable the required functionality. If you are up to living dangerously, you can mark any local storage device as an SSD. Continue reading

VMware 10G NIC Performance Evaluation

For the last few years we have been running IBM x3850 x5 servers in our cloud, with Emulex 10G NICs for all of our networking needs. One of our services was starting to run out of steam, and we picked up a pair of HP DL580 G8 servers for the needed horsepower. These servers were configured with Intel based 10G NICs. At the time of the purchase, our main concern was to get the maximum CPU performance and minimal attention was paid to 10G NIC selection.

As we put these servers into production, we noticed that the VMware iSCSI performance on the new HP hosts seemed especially good. The E7-8891v2 Xeons undoubtedly have a large role to play in the improved performance, but we began to wonder how much of the performance improvement can be attributed to the 10G NICs. Not one to let such thoughts sit idle for long, I asked our friends at Zones if we can borrow a few 10G NICs for performance evaluation. Within a few weeks I had dual port Intel and Mellanox 10G NICs in hand for testing, in addition to the Emulex NICs already present in our IBM hosts. Continue reading

PWM Based LED Driver

** Updated code for better performance and stability [26 Feb 2015, rev.3]

It has been quite some time since my last post – as often happens, life intervenes and this time just a bit too much hospital time both for myself and one of my kids. Things are good now and normal can resume…

Black-Decker-FSL18FL-Firestorm-18-volt-FlashlightFor years I have had this Black&Decker FireStorm FSL18 flashlight, but hardly ever used it due to its anemic light quality. The fixture is powered with an 18v battery pack and uses a KPR18v0.3A bulb putting out 7 candlepower when running at 18 volts. 1 candlepower = 1 lumen. Compared with the brightness of the 12v power LEDs I have been working with lately, the brightness from this incandescent bulb is not much better than a glassed candle.

The trigger for upgrading this flashlight came one day when the wife complained an LED lightbulb had failed in her workshop. I replaced the bulb, but rather than throw it away, I took it down to my workshop to disassemble and identify what had broken. Continue reading

Upgraded My HP Touchpad in the Nick of Time

Back when HP was having its big Touchpad Firesale, my wife picked one up for me as a Christmas present. Loved it. A few years on, however, I find I am using it less and less, as it does not do the things I need. Simple things, like Citrix remote sessions, so that I can quickly login to work and help when an issue comes up. Even Netflix or Vudu would be great.

I had heard of people working on an Android build for the Touchpad, and after a few hours of poking around, I decided to try it out. I mostly worked with the information in this page: Continue reading

Featured on

Imagine my surprise on Monday morning, when WordPress sent me an alert of significant activity on this site. Over 40 visitors within the last hour – that is very unusual. Usually it is much less than that per day. I took a look at the detailed statistics and all of the hits were coming in from It appears someone had submitted my article describing a cheap power LED driver to their editorial team, and it got accepted! YAY! Continue reading

Manually disable vmreplica state (unable to extend disk)

Just ran into an issue with a VMware VM that was at one time replicated offsite using VMware’s replication tool. For some reason, when the service was decomissioned, (at least) one of our VMs was still marked as a replicated machine. When a VM is marked as active, then it will not be possible to extend the disk drive. In our case it appears that it was also in the middle of a replication, long since abandoned.

To fix, we found this article: StuffThatMightBeUseful

In the article, the author points out that the VM needs to be shut down. Probably better if the VM is down, but in our case we did not have this option and changed the setting on the running VM. Worked and did not crash. yet.

The steps are simple:

  1. Find the VM_ID (number in 1st column): vim-cmd vmsvc/getallvms |grep “name of your VM”
  2. Confirm current state: vim-cmd hbrsvc/vmreplica.getState VM_ID
  3. Fix: vim-cmd hbrsvc/vmreplica.disable VM_ID