We have added an RSS feed for our articles – you can now get our new posts in your email or RSS feed app! On the right-hand side under the tag cloud you can enter your email, or enter the following url into your RSS reader:
https://sotechdesign.com.au/feed/
Enjoy!
Here’s another oldie but a goodie:
tracert -h 66 216.81.59.173
The above is for Windows command line – the “h” flag is to see all 66 hops necessary to get the full effect! Enjoy 😉
For those that haven’t seen this before, someone reminded me of this the other day:
telnet towel.blinkenlights.nl
Enjoy 😉
If you have upgraded your kernel you will have found that Ubuntu keeps the older ones around, which can be handy if something breaks in the newer kernel and you have to boot from your old system. Over time, however, these can add up in terms of the amount of space consumed – at around 150MB per kernel you could easily find yourself with over a GB of old kernels if you’ve upgraded enough times. In this example the system we are using is Ubuntu 12.0.4.2. If you’re using Ubuntu Desktop, open up a terminal window – if you’re using Ubuntu Server, log in as usual and run:
uname -r
to see which kernel you are currently running. Make sure not to delete this one. Now, to see a list of the installed kernels, we run:
dpkg –list | grep linux-image
This command lists the installed packages and filters the list to include only those which have “linux-image” in them, which should only be your kernels. Your list should look something along the lines of:
ii linux-image-2.6.32-33-server 2.6.32-33.72 Linux kernel image for version 2.6.32 on x86_64
ii linux-image-3.2.0-35-generic 3.2.0-35.55 Linux kernel image for version 3.2.0 on 64 bit x86 SMP
ii linux-image-3.2.0-38-generic 3.2.0-38.61 Linux kernel image for version 3.2.0 on 64 bit x86 SMP
ii linux-image-server 3.2.0.38.46 Linux kernel image on Server Equipment.
To remove a kernel, run the following:
sudo apt-get purge [kernel]
Using the above list, say we want to get rid of 3.2.0-35. In that case the command would be:
sudo apt-get purge linux-image-3.2.0-35-generic
Once you have removed your unwanted kernels run:
sudo update-grub2
This will update the boot menu accordingly.
Found this little gem when going through some old gear a few weeks ago;
Hard to believe it was only 13 years ago – feels like much more. Oh the memories…
Happy New Year everyone.
Enabling SSH is handy if you want to remotely access the back-end of your system; it can also be really handy for moving files around and transferring data to and from Linux systems or VMs securely and quickly. There are security risks with doing this; if anyone logs in to the root account of your server they will be able to do whatever they like, even destroying all of your VMs, powering them on or off and who knows what else. We would suggest making sure that your LAN is secure and not to open your server’s SSH ports to the internet (you may want to do this so you can log in remotely). If you are interested in doing the latter, use an RSA key for your login and disable text-based authentication (see our guide here)!
Firstly, open up vSphere Client, log in and select the server you wish to enable SSH access on. Go to the Configuration tab like so:
In the “Software” pane on the left, select Security Profile:
On the right-hand side of the Services heading, click Properties:
Here you can see ours is already running (look for SSH -> Running) – if yours is off it will say Stopped. Click on SSH and then click Options…:
Note that if you click “Start” then select “Start and stop with host” it’ll stop the service again. You can get around this by selecting “Start and stop with host”, closing the dialog box, reopening it and starting it manually before closing it. If you don’t want to leave SSH on for longer than you need to just start it using the Start button and come back to this dialog box after you’re done and stop the service again. If you are confident that the security risk is worth it it is convenient to have it start and stop with the server.
…and you’re done!
If you have found one of your datastores is greyed out/inactive one solution is to unmount it and add it again; sometimes ESXi won’t let you do this, giving the following error message:
“Error: The resources ‘ip.of.data.store:/data/location’ is in use.
Error stack: Call “HostDatastoreSystem.RemoveDatastore” for object “ha-datastoresystem” on ESXi “ip.of.your.esxi” failed.
# esxcli storage nfs list
That will list all of the datastores currently available to ESXi via NFS. Now to unmount the inaccessible datastore we run:
# esxcli storage nfs remove -v [inaccessible datastore name, here codexSSD]
This will return us to the prompt like so:
If you list the available datastores again it should be gone:
# esxcli storage nfs list
Log out and check your vSphere Client’s storage tab – it should be gone there, too. If it hasn’t disappeared refresh the view. From here you should be able to add the datastore again without hassle.
One of the most asked-about combinations we’ve done recently has been putting a H100 into a storage chassis; so long as your motherboard isn’t too large (e.g. SSI EEB or equivalent) it’s quite easy to do.
On the top of any modern Intel CPU you will see the country of assembly printed, and it will be either Malay or Costa Rica. Back in the day this could mean the difference between a chip with excellent overclocking potential and a dud; how about now?
In a nutshell, no more difference than you get with normal batch-to-batch variation. Intel’s Copy Exactly program apparently works as intended – controlling every possible controllable variable involved in the assembly process to eliminate any differences. You can read more about Copy Exactly on Intel’s website (link) – the origins of this process actually date back to the 1980s.
So if you end up with one or the other, relax – neither one is going to automatically mean a better chip.
