Tag: How To
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XenServer 6.2: How to boot a VM to CD/DVD rather than disk
We had a situation recently where a customer was experimenting with XenServer 6.2 and Ubuntu VMs; he accidentally powered off the VM during a distribution upgrade and the VM would only boot with a read-only filesystem. Loading an ISO into the virtual CD drive didn’t do the trick; there’s no obvious way of booting…
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How to install XenServer 6.2 – Step By Step
With the recent public availability of XenServer 6.2 there are an increasing number of people wanting to try it; here is a walk-through of an install so that you know what to expect if you want to try it yourself. In this example we are using a NFS datastore on the network to store…
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Ubuntu: Bringing a detached tmux session back
If you’re just starting out with tmux you may have installed it, set up a session, detached and then… what? To re-join your detached session, simply run: tmux attach and you’re back in business.
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Ubuntu: How to change tmux’s ctrl+b binding to ctrl+a
If you’re used to screen you’ll be in the habit of using ctrl+a, for example detaching a session with ctrl+a then d – if you make the move to tmux it’s ctrl+b then d, which can take some getting used to. Often it’s easier to make tmux get used to you! To change tmux…
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Ubuntu: How to create a file or folder using today’s date
This is a useful little trick to use in your scripts – particularly for things like periodic backups. For a file: touch $(date +%F) creates the file 2012-11-18 For a folder, let’s add the time after the date: mkdir $(date +%F-%H:%M) creates the folder 2012-11-18-09:00 We can use…
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How to exclude results from grep
Sometimes you may wish to further filter grep output, such as in the following situation: # zfs get all | grep compressratio backup01 compressratio 1.23x – backup01 refcompressratio 1.00x – backup01/data compressratio 1.50x – backup01/data refcompressratio 1.50x – backup01/photos compressratio 1.05x – backup01/photos refcompressratio 1.05x – Here we only really want to see…
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ZFS: How to check compression efficiency
If you have enabled compression on a ZFS folder you can check to see just how much disk space you’re saving. Use the following command: sudo zfs get all [poolname]/[folder] | grep compressratio An example: sudo zfs get all backup01/data | grep compressratio returns the following: backup01/data compressratio 1.50x …
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Ubuntu: How to list drives by ID
If you’re creating a zpool on Ubuntu you have several options when it comes to referring to the drives; the most common is /dev/sda, /dev/sdb and so on. This can cause problems with zpools as the letter designated to a drive can change if you move the drives around, add or remove a drive –…
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How to find kernel version in Ubuntu 12.04 Precise Pangolin
Note: This also works in other versions of Ubuntu, such as 11.10, 11.04, 10.10, 10.04 and earlier. Sometimes you may wish to find out which kernel you’re currently running; fortunately, this is quite easy to do with the uname command. If you’re running Ubuntu Desktop, open up a Terminal; if you’re using Ubuntu Server…
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How to reset a ProCurve 2510-24g to default settings
Here’s one someone asked me today – it’s reasonably straight-forward, though not necessarily obvious: Press in both the Clear and Reset buttons (tiny buttons on the left edge) Release the Reset button after the port lights come on (~2 seconds) When the Self-Test LED starts flashing (to the left of the Clear and Reset…