There's a Windows system statistic that can be an ironclad indicator of resource contention...but most folks never seem to consider it.
Each network interface card (NIC) in your system has an associated output queue; the TCP/IP stack (WInsock) drops packets in this queue, from which the NIC processes them and puts them out on the wire. Obviously, this number should always be very low; Microsoft states that any value higher than 2 indicates a NIC/network bottleneck. In recent customer situation, I've seen queue lengths as a high as 8-10; a colleague claims to have seen queue lengths as high as 25!
The first steps in alleviating high NIC output queue lengths is (duh) to ensure that network connectivity (e.g. the local switch/router) is not suffering from congestion. The second step is to ensure that one has installed the 'latest and greatest' NIC drivers.
Here's where things get interesting, from a system troubleshooting point of view; the LOOPBACK adapter also has an output queue. This is critical, for two reasons:
- Loopback adapters exist only as a construct in RAM, so memory contention can affect loopback adpaters disproportionately, and
- Many applications, particuarly server applications, use loopback connections for interprocess communication.
Now, there's no NIC for the loopback, so high output queue lengths on this adapter are indicative of memory contention. I've seen cases in which high loopback output queues led to "connectivity problems" in the system/application logs, but the root cause was determined to be extremely high paging/swapping and overall memory contention among processes. Troubleshooting problems here will require examination of overall system memory utilization, paging/swapping, et cetera.
We aren't done, however; if virtualization is involved, our troubleshooting will be pointing us in a different direction. When running in a virtual machine, what the application "sees" as its NIC is a virtual adapter; all Windows virtualization systems handle these 'pseudo-interfaces' in RAM. So, we obviously can't go update NIC drivers; instead, high NIC output queue lengths in VM environments usually indicate one of two things: either the physical NIC of the virtual host is so overloaded that it isn't picking up the packets from the various "virtual adapters" of the individual virtual machines, or (since they're all handled via RAM constructs) the virtual host is suffering from memory contention. Keep in mind that you may not see high CPU/memory utilization on the virtual machine running Windows, since it only 'sees' what the virtual host tells it to see; you need to look at CPU/memory statistics on the virtual host itself!
If you're running Windows systems, take a look at Output Queue Length in Perfmon.
My digital music library has grown considerably over the last two years; I have well over 20000 tracks, in genres from Russian death metal to K-pop and barbershop quartets. Since I pick up the bulk of my music online (via promotions and samplers), I find that my MP3s exhibit a wide variety of tags (or, on occasion, no tags at all). Compounding my difficulty is that fact that I use multiple applications to access/manage my music; it seems that my primary applications--iTunes, Zune and MediaMonkey--don't like to handle tags in quite the same way. How, then, am I supposed to tag my libraries such that my flock of apps is happy?
I recently won a 16Gb Blackberry PlayBook; this was a Cool Thing on several fronts. First, I'm an alpha geek, and not having a tablet of any sort just felt wrong. Secondly, 3 of my kids have iPads through their high school, so I will admit to a wee bit of Tablet Envy. Finally, I really wanted to see just how much the tablet form factor would help, hinder or change my style. So, I've had this thing for just over a month, and I took it to Lotusphere 2012 to see how well it would work with my on-the-road style.
Well, I finally found the "right person" who could get me onboard with Sametime United Telephony. (Of course, I found that person at Lotusphere!) So, I sat down to enable SUT on my Windows 7 desktop. All went according to plan until I actually made an inbound test call to my SUT number...it worked once, then everything failed. It went beyond just SUT; I had no audio in any application, no calls, nothing.
One of my Twitter friends pointed me to the folks at
It's snowing outside, and--as usually happens--I found myself humming a song. Not just any song, mind you, but one particular song that ALWAYS comes to mind when I watch a snowfall. It isn't "Let It Snow," or even "Winter Wonderland," but allow me to explain...
Every so often, I'll just toss the odd search term into Google and see what happens. Tonight, I was led to the home page of Rosoboronexport, the state-owned Russian arms agency. For some reason, I don't think of advertising and marketing as something to be applied to submaries, air defence systems or missiles; I was quickly disabused of such notion. The Rosoboronexport site is full of hype and glitz, including (if one selects the "Catalogues of Products" link from the "Menu Open" button) full-size PDF catalogs for land warfare, naval, air force and air defence systems. Interesting stuff...