New HDD 20Tb format overhead

[CharlieDaves]

I've just formatted a new 20Tb HDD, (USB3 External Holder 4bay, only this drive plugged in).
I selected ext4.. When completed, I had the following

1.unallocated 8Mb (it's on every drive I have.) So this is normal
2. 16Tb Partition
?? 3.... 2.17TB unallocated.... ?

Q- Can someone please explain to me why I have a 2TB unallocated space ?
Is this kubuntu ?
Is this USB, or External Holder ?
Is this the OS.. ?
Is this a PEBKAC error ?

[claydoh]

It's probably ext4 defaults for reserved space and/or the default block sizes in the partitioning tools, and all sorts of technical mumbo jumbo

https://wiki.archlinux.org/title/Ext4#Reserved_blocks

https://www.reddit.com/r/DataHoarder...n_500gb_46576/

Maybe someone who understands this better can chime in.

[oshunluvr]

It's probably ext4 defaults for reserved space and/or the default block sizes in the partitioning tools, and all sorts of technical mumbo jumbo

IIRC, this refers to a portion of the formatted space being reserved, not "raw" space. To confirm this I did a test using a 20GB virtual drive. First, I formatted it using defaults and mounted it:

Filesystem         Size     Used Avail     Use%    Mounted on
/dev/vdb1          20464208 2072 19397280  1%      /mnt

Then I reformatted it using zero reserved blocks:

Filesystem         Size     Used Avail     Use%    Mounted on
/dev/vdb1          20464208 2072 20445752  1%      /mnt

One can see the size of the partition and file system did not change, but the amount of free space did.

I can think of no reason for the whole device not to be used normally. The first (sectors 34-2047) and last few sectors are not used to keep the 2048 sector alignment, but that amounts to KiBs not GiBs and most certainly not TiBs.

My first question is how did you partition and format the drive? The first test was done with KDE Partition Manager and the output is from basic mount and df commands. Then when I reformatted it to remove reserved blocks, I used mkfs.ext4 in Konsole.

I am guessing the issue is with the controller in the USB device and not the drive or formatting. See if it will let you add an additional partition.

I suspect if you check the detailed specs of your USB device, it will have a 16TB limit.



Also, FYI, none of my internal or USB drives have 8MB unallocated space. I believe this is a Windows thing.

[CharlieDaves]

I used kde Partition Manager, to find the drive and format it. This is why I am so puzzled. Yes. Normally there is (or has been) some sort of 8 Meg unallocated, and my thoughts have always been 2^2 cannot be divided equally into the 20Tb ( 21,990,232,555,520 )

I used the default settings. GPT Table, then select format