Tag: check

  • Checking whether nginx cache is working

    Just set up nginx caching and wondering whether it’s working properly? You can check it pretty easily:

     

    curl -I URL.goes.here

    That should return a bunch of information, but the important bit is:

    X-Proxy-Cache: MISS

     

    Well, in this case it’s not working. If it’s working you’ll see a HIT there.

  • 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  –

     

    Here we can see we have a compression ratio of 1.5x. Compression is an excellent way of reducing disk space used and improving performance, so long as you have a modern CPU with enough spare power to handle it. Some data will not be easily compressible and you may see less benefit – other data will be much more compressible and you may reach quite high compression ratios.

     

    If we run the same command on a folder full of already-compressed RAW image files:

     

    sudo zfs get all backup01/photos | grep compressratio

    backup01/photos compressratio 1.05x

     

    …we can see that they do not compress as easily as the documents in the data folder, giving us only a 1.05x compression ratio. You can see the compression ratio of all of your ZFS pools and folders with the following:

     

    sudo zfs get all | grep compressratio

     

    Check your own datasets and see how much you are saving!