That calculator has been correct for all sized drives for me. There is minor variation in plot size but it’s not enough to throw off that calculator.
I also have a 6TB drive where I did not limit the numner of inodes and only get 54 plots
Check my /dev/sdb1 (mounted on /mnt/dest/d) vs /dev/sdd1 (mounted on /mnt/dest/b)
snef@main:~$ sudo tune2fs -l /dev/sdd1 | grep "Inode count"
Inode count: 183144448
snef@main:~$ sudo tune2fs -l /dev/sdb1 | grep "Inode count"
Inode count: 715408
snef@main:~$ df /mnt/dest/d
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdd1 5813267548 5739504132 73747032 99% /mnt/dest/d
snef@main:~$ df /mnt/dest/b
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb1 5858874808 5845938052 12920372 100% /mnt/dest/b
snef@main:~$ ls -l /mnt/dest/b/plo* | wc -l
55
snef@main:~$ ls -l /mnt/dest/d/plo* | wc -l
54
snef@main:~$
For Chia plot HDD, we don’t need such a high number inode, it is wasted HDD space, each inode occupies 256 bytes, so in case of snef’s 2 HDDs, the HDD with 715408 inodes save ~43.5GiB space compare to HDD with 183144448 inodes. This is align with the actual different available space.
Once the partition is created, the number of inodes cannot be changed (reformat is required). We can decide the number of inode when we create a partition (e.g. using mkfs.ext4 command) by:
using –N option as snef suggested. This is to set a specific number of inodes regardless of HDD/partition size. I think this is the best option for Chia plot HDD.
using –i option (e.g. sudo mkfs.ext4 -i 196800 /dev/sd??) by specifying the bytes/inode ratio: the higher the value the smaller number of inode, it seems the default value is 16384 bytes per inode (vary depend on version/software used). The partitioning command/software will calculate the number of inode = partition size divided by bytes/inode ratio. For HDD only used to store Chia plots, this number should be high (> 4MiB)
using –T option (e.g. sudo mkfs.ext4 -m 0 -T largefile /dev/sd?? or sudo mkfs.ext4 -m 0 -T largefile4 /dev/sd??): largefile = i option of ratio 1 MiB every inode and largerfile4 = i option of ratio 4 MiB every inode