It has been a while since I last posted, but thought this one might be of interest to a few of you, especially since I keep running into it every so often.
Some time ago I did a performance analysis of multiple manufacturer NICs. As a part of that test, I also tested the impact of changing the TCP congestion algorithm in VMware from the default New Reno to Cubic. The cubic algorithm consistently delivered better throughput results in the tests, and since then I have updated all of our hosts to use this.
Unfortunately, if the algorithm is set via the VMware 5.5 vCenter Web Interface, not all of the required changes are applied properly to the target ESXi host and upon reboot, the host is unable to connect to vCenter. It took quite a bit of work with VMware until we discovered the root cause. Fortunately, we did identify a simple workaround, documented here: https://communities.vmware.com/thread/506836 Continue reading →
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 →
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 →
** 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…
For 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 →
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.
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 dangerousprototypes.com. It appears someone had submitted my article describing a cheap power LED driver to their editorial team, and it got accepted! YAY! Continue reading →