the Zen of Communication.

Running some performance tuning, the app needed to know how many flops (floating point operations) per cycle the system could handle.

I used SiSoftware’s Sandra benchmarking app. It told me that my Intel Pentium D Dual Core 1.8ghz proc was producing 10.86gflops, but not the flops per clock cycle.

From this we know: a) the total gigaflops (10.86), b) the number of cores (2), and c) the number of clock cycles per second (1.8ghz)

Example of the standard formula:
The formula to determine total gigaflops is:
Flops per cycle x # of Cores x Clock speed.

This involves four values:

a = flop per clock cycle
b = clock speed (ghz)
c = cores
n = gflops

For a dual core 3ghz system with 4 flops per cycle, we can deduce 24gflops (a x c x b = n, or 4 x 2 x 3 = 24) . But I only have the total gflops, clock speed, and number of cores.

Reverse algebra:

a = n / b / c

Or in my case:
10.86 gflops / 1.8ghz / 2 cores = 3.01 flops per cycle (per core). So the E2610 chip at 1.8ghz produces 3 flops per cycle per core, or 6 flops total. Ta da.

Note: It’s worth mentioning that in this case, 10.86 gflops and 1.8ghz seem like closely related numbers, and that it would be quick to figure out how many gflops a system can handle by its clock speed (i.e. 1.8ghz equals 10.86gflops).  This is not the case.  In the first example of a dual core 3ghz proc producing 24gflops, you can’t deduce the one from the other.  It was just a coincidence in my case, so don’t do that.

Setting up a new pool (persistent linked clone, in this instance) for VMWare View 4. Had the template built, took a snapshot, then tried to create the pool. Got all the way through setup to select the template and snapshot, but voila. Snapshot wasn’t there.

VMWare View templates require the snapshot to be taken WITHOUT the VM memory state. If the memory state is taken with the snap, the snapshot isn’t available – except it won’t tell you why.

VMWare also highly recommends/suggests that the VM template be powered off. This makes a lot of sense, and you really should, but I had two snaps taken with the system powered on which I built VDI Persistent Linked Pools from, and 10 desktops worked fine.

A client is using a mixed environment, with several VMWare ESXi clusters, and several ESX clusters.  They’ve been running a number of maintenance tasks through SSH on the ESX clusters, but believed one could not get to a console under ESXi 3.5.  I found a quick howto:  http://www.vm-help.com/esx/esx3i/ESXi_enable_SSH.php

The short of it is you have to enter a debug mode in the console.  From the main console window, press ALT+F1 to get to the console terminal.  You’ll start out with:

(names have been changed to protect the innocent).  And after hitting ALT+F1, you’ll get:

Whereupon you’ll type “unsupported” (no quotes) and hit enter, and it will not be visible.  Just trust me, it’s there.  You may need to try it a couple of times if the console has had any keypresses still in the buffer.  Afterwards, you’ll get:

Enter your root console password here.  You’ll get dumped to a linux prompt.  Know this: Yes, it’s “linux”, but it’s stripped.  Many rudimentary functions are not present. 

From here, edit /etc/inetd.conf (using vi).  Scroll down until you find the line with “#ssh” .  Remove the # to enable the line .  (the vm-help.com page has detailed vi instructions.  I won’t go into those here.  But here’s more help) 

Once you’ve uncommented the ssh service, write and quit.  Then run /sbin/services.sh restart. 

Now, every other howto out there would leave you believing you should be all set.  If you’re anything like me, you’ll reboot your host, and then wonder where you went wrong.  In life.  After all, 5 or 10 how-tos have the same instruction set, and everyone else said “hai this rox kthxbye!”.  And yet I followed the instructions and I still had no joy.  I killed the inetd process numerous times, and had no joy.  What was a frustrated sysadmin who enjoyed such problems as this to do?  Get cracking.

I eventually hit the logs and discovered a couple of parameters were missing for their implementation of the ssh server, dropbear.  The path in the /etc/inetd.conf file was simply /sbin/dropbear .  For kicks, I tried to run ./sbin/dropbear.  It, in a world of generosity, spit out a list of symlinks I needed to create.

If I’m remembering this right, I did what it asked but it still didn’t work.  So, the actual path I ended up using in /etc/initd.conf was:

/sbin/dropbearmulti [tab] dropbear ++min=0,swap,group=shell –i

This calls the dropbearmulti app, and instead of using the symlink method it’s asking for, just tells it “here, run the server, and here’s your arguments.” .  It seems to be working, because several weeks and a few reboots later I’m SSH’d into the server to pull up the details for this post. 

Just bought a series of HP DL360s from a firesale.  AOL was refreshing a datacenter, these things were dirt cheap.  I’ve outfitted one with a pair of UW320 hotswap 72gb drives, but I’m figuring out a mod to put SATA drives in – cheaper, readily available, and don’t require ubercash and ebay to pick up if one dies.  It looks straight forward enough.  From my initial pokings, the SCSI backplane just lifts out.  The power connector is a single molex to the backplane that distributes it to the two drives, so I need a y-cable.

Empty drive trays are $10 a pop, so I’ll use those to lock the drives in place.  I have one outfitted with 4gb ram already which should be enough for most ops.  They’re dual-proc Xeons (single core, no VT) at 2.8ghz, and should make nice dogfood boxes for labs w/ VMWare GSX server.  Once I load test them, know they’re stable and won’t crap out on me, I may replace my dual p3-800 server which hosts my critical stuff.  At the very least, with a cheap SATA raid array, great media and file server.

www.nautilusnet.com was the company.  The chassis were $20 a pop, came with the procs and 1gb ram, no drives.  They had a 3.04ghz model for $30, same outfit (240 mhz doesn’t make that much diff. to me).  The company has everything else needed to outfit them – drives (36 or 72gb), memory kits, and redundant power supplies.  I’ve put in three orders with them now, and they’re awesome to work with.

Disclaimer: I’m not paid nor do I benefit in any way from this plug.  I don’t get kickbacks, gift cards, taken out for free drinks by the sales staff, free gear, logo’d jackets, tote bags, bumper stickers, or any special sale price on equipment.  They’re good people that do a good job and are worth a mention.

I also just bought a Linksys WMP300N PCI Wifi N card, and a WRT600N “Ultra RangePlus Dual-Band Wireless-N Gigabit Router” .  I installed them last night in hopes of getting better “reception” with my home-theater box (which I use for Netflix On Demand, and MS Flight Simulator – rest in peace – on my TV), but ran into a few hurdles configuring the 5ghz N signal.  A post will be forthcoming about that and some mild insanity once I stop foaming at the mouth about the Linksys wifi manager software.

I run VMWare on my laptop.  I use it for older Windows distros (’95 and 2000 – ’95 is the only thing that will sync with my Newton!), and I have a couple of Linux distros which I run when I have time to work on them, or when I need special networking services.  The problem is, I don’t run VMware all day every day.  In fact, there are some weeks I don’t run it at all.

VMware (and Microsoft VirtualPC) runs services in the background to give it networking support – allowing both your VM guest and your host to share a network card, to set up the "virtual" network lab (where your guests are isolated from your actual network, but they can all talk to each other and the host), etc.  There are four main services that start automatically in total:

VMware Authorization Service
VMware DHCP Service
VMWare NAT Service
VMware Virtual Mount Manager Extended

There’s also the VMWare Agent Service, but this is set to manually start, and is probably invoked by VMWare itself (I’ve never seen it running, so I can’t say for certain).

These four started services probably don’t consume a lot of resources – I’ve rarely seen them above 3 or 4 mb of memory usage, and minimal proc usage.  But they do load drivers into the network stack.  If you take a look at your protocols and drivers in the Network Properties page you’ll see the VMWare Bridge Protocol (Virtual Machine Network Services is for VirtualPC, and is also required for networking support in VPC machines).  Again, these are only used for guest OSes, so they’re not required for typical network operations (getting a DHCP address, surfing the web, checking email, etc.). 

Every once in a while though, I’ve had a VMWare error pop up, even though VMware was never started.  So I decided to stop VMWare from starting automatically, and require my action to turn the services on.  This will keep the services from loading, chewing up memory, but most importantly prevent attaching unnecessary active services to the network card.

First set those four services to start up manually, rather than automatic.  (I’ll put screenshots up here when I have a moment, but it’s done from the Administrative Tools\Services MMC).  Once they’ve been changed to manual, either reboot or just stop them by hand (right click the service, stop).  Then I wrote the following script into a batch file that I named "Vmware-Start.bat"

net start vmauthdservice
net start vmnetdhcp
net start "vmware nat service"
net start vmount2

I didn’t write a full batch script with the echo cmds etc, mainly because I’m not a coder so I have little to no clue about proper syntax without an awful lot of googling, but secondarily because for net start and stop commands, it’s just not needed.  [Please post dissenting opinions if you have them, I'd like to get my scripting skills up a bit.]

So those four lines are used to start the VMware services, when I need to open VMware.  These next four lines were put into another batch file named (you guessed it) "VMware-Stop.bat"

net stop vmauthdservice
net stop vmnetdhcp
net stop "vmware nat service"
net stop vmount2

Save the scripts into the \Program Files\VMware\ directory, and create shortcuts to them.  Put the shortcuts on your desktop (I put mine into the VMware start menu group).  Each time you want to run VMware, you’ll need to run the Start batch file, and when you’re done with VMware you can run the Stop batch file.  This will give VMware everything it needs to run effectively, and keep services offline when you don’t need them.