Can't get the whole disk mounted

[peerwal]

Hi everybody,

My PC is using 2 500 GB disks that were set up as BIOS-controlled raid array. I had to disable the BIOS raid setup, as grub obviously set up an additional software raid array during the upgrade to Kubuntu 16.10. Now, after installing Yakkety on my first disk, i am trying to mount the seconf disk to one of my home directories and I had the following problems:

The partition I created had only 472 MB of free diskspace although the file manager definitely diplayed it as to be empty at least in the files section. I then shredded the partition, created a new partition table, and checked/repaired/optimized the partition using the kde partition manager. This already helped a lot but the ext4 partition I mounted still only has 434 GB instead of 465GB and I am not able to find out what it is that takes the remaining diskspace.

I just found out that the free disk space of the partition sometimes still decreases after deleting the partition and creating a new one. Dolphin says there are only 415 GB left, although the folders/files tree is completely empty except for 'lost+found'. The partition manager displays a full size of 465 GB with 23 GB being used. Could it be that grub still uses /dev/sdb as software controlled raid disk? How can I find out?

Any information is hghly appreciated.

[oshunluvr]

EXT3/4 filesystems pre-allocate inodes to prevent false "disk full" errors if a large number of files are stored on the disk, usually like 5% of disk space, so 23 GB sounds about right. If you know you're not going to have a large amount of files on the filesystem in question you can reduce the reserved space by "tuning" the filesystem. However, I wouldn't do that. You might use up all the inodes before the drive is actually full. Besides. the space isn't actually "lost" it's just reserved. If this is really a concern for you, use a filesystem that assigns inodes dynamically like XFS.

Also, the math gets wonky when converting real world sizes from manufacturer claims, etc. Sometimes MB is used, other time MiB is used.

In the end the actual difference will be nominal. IMO, you're overthinking this just a bit.

[peerwal]

Hi oshunluvr,

Thanks very much for the information. I am not at all concerned about the 'extra' disk space, I was just wondering.

[oshunluvr]

Some distros use XFS for /home partitions partly for this reason. Dynamically allocated inodes will result in a little more space if you tend to have larger files as homes often do - like videos and pics, etc. Nowadays with drive space so cheap most people don't even notice the reduction in identified usable space like you did. I hope my "overthinking" comment doesn't discourage you from questioning and exploring reason for things like this and if it did, I apologize. When I read it back just now I could see how it might come across as discouraging. I didn't intend for it to be, I meant only to indicate all is well.

If you're interested, you should explore other filesystem options like XFS or BTRFS (my choice) as well as some others. They all tend to have their benefits and failings but if you have a special use-case like large amount of video storage or some other use out-of-the-norm, you might benefit from a different filesystem rather than the default EXT4. I use BTRFS because of all the features few other filesystem have and I've written about it extensively on this forum.

Welcome to KFN. I look forward to your future questions.

[peerwal]

Thanks again for the additional information. Don't worry, your comments did not sound discouragingly to me. I think, I learned quite bit again and I appreciate the support I get at KFN. I think, it's one of the most competent forums for Kubuntu topics.

Actually, Iwas not sure, whether i should use BTRFS as it is quite a new FS and I wondered, whether it would be stable enough. However, I will look at your comments about it and, if possible, step up to BTRFS.