Socks Blockchain supports k28 plots of 5Gb so you can utilise the most of the hard drive to increase chances to farm pair of socks. k28 plots have the same structure and in fact have no difference to classic k32(101Gb) except of the amount of entries.

For the 8Tb HDD there is about 90Gb of free space left. Obviously, k32(102Gb) plots can't be fitted there, so it's a wasted space. Instead of wasting space, the remaining could could be filled with 7x k29(12Gb) plots and 1x k28(5):

7⨉12Gb + 1⨉5Gb = 89Gb

It's just enough to fill the remaining 90Gb space.

Create k28, k29+ plots

Using Windows and Linux GUI

Since release 1.2.3 it's possible to plot right from the Socks Blockchain GUI.:

Select k28 plot size in GUI

For CLI / Linux / MacOS

$ . ./socks-blockchain/activate
$ socks plots create -k 29 --override-k -n 100 -r 2 -t /mnt/chiatmp/ -d /mnt/chiatmp1/out/anna-socks/

Replace -k 29 with any required number

More generic:

$ socks plots create -k K_NUMBER --override-k -n AMOUNT_OF_PLOTS -r 2 -t /mnt/TEMP_FOLDER/ -d /mnt/DESTINATION_FOLDER/

Can I mix plots with different k?

Yes, you most certainly can mix different plots as long as they're plotted for the same public and pool key.