Now that we have created the ZFS Mirrors in the Linux system which point to four other SCSI drives of 10G capacity each, our two existing mirrors of two drives each are theoretically capable of accessing data of at least 20G in size. However, due to the overhead for keeping track of this data in the filesystem, our Linux system show a total data access space of around 19G.
If I open the Linux Terminal and run a listing of the storage using the ls command, then change directory to the zfspool to the subdirectory called datapioneer under the data subdirectory of zfspool, and then run the df -kh command, the output indicates the 19G blocksize that I mentioned above.
The total available space in the /zfspool/data/datapioneer dataset directory is 19G. This can be seen both in the Terminal and in File Manager as shown above. Now, since I changed ownership of this directory to datapioneer and set the permissions on the directory to 755, as datapioneer in the Linux system I should be able to touch this directory and create a file, name the file, add some content to it, and save the file under /zfspool/data/datapioneer with a total of 19G of available space in which to do so. This is demonstrated below in the Terminal:
Here, a new file was created called newFile.txt containing the text shown in double quotes following the echo command which is then redirected as output to the file itself. Opening this file in File manager shows a clearer picture in the GUI:
Thus, we have created an additional 20G available ZFS pool of 4 SCSI drives of 10G capacity each that allow us to expand our available space across all four drives in the Linux system for storing our files which can be also be shared on the network.
If, in the future, additional storage space is needed, then all that is required is to install the additional SCSI drives, create a new mirror, and add them to the ZFS Pool expanding the total space across all drives in the Linux system. This is easily performed under OpenZFS. In this example I used small capacity SCSI drives, but I could just as easily add 1, 2, 3, or 4TB SCSI drives in a mirrored fashion to greatly enhance available storage and doing so is accomplished quite easily, as you can see, with the implementation of ZoL in Linux.