I finally got the courage up and did a reinstall. The partitioning proposal got up to sda8 or sda9! In the end, I selected “shrink Windows as needed” and “remove linux partitions.” The install went pretty smoothly but not completely. I asked to preserve my user, even though I have backed up all the files I wanted to preserve. An error message came up, as it neared finishing, that said It could not complete some task. I selected “ok” and it continued the install. A moment later, it said it could not create my user. It said “create” not “copy.” I selected “ok” and installation continued. It finished in short order and booted (I had to work around that BIOS file issue) to a splash screen with no user. I logged in as root and created my user. Except for getting my desktop to look the way it used to; and adding programs that I want (boinc, latte dock, k3b etc.) it is working very well.
Here is my new partition setup. The installer gave me exactly what I wanted.
fdisk -l
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: ST1000DX001-SSHD
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 23547642-B9DF-43CB-B0DA-165D29294539
Device Start End Sectors Size Type
/dev/sda1 2048 534527 532480 260M EFI System
/dev/sda2 534528 796671 262144 128M Microsoft reserved
/dev/sda3 796672 1312665599 1311868928 625.5G Microsoft basic data
/dev/sda4 1887537152 1889585151 2048000 1000M Windows recovery environment
/dev/sda5 1312665600 1887537151 574871552 274.1G Linux filesystem
/dev/sda6 1889585152 1893779455 4194304 2G Linux swap
I specifically did not ask for a /home partition based on an opinion above. Earlier I posted that I could not download the latest offline installer for lack of room. My linux partition was 86% full. Here is what it looks like now:
df -l
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 4096 0 4096 0% /dev
tmpfs 4031172 181116 3850056 5% /dev/shm
tmpfs 1612472 9908 1602564 1% /run
/dev/sda5 287435776 7617312 278157536 3% /
/dev/sda5 287435776 7617312 278157536 3% /.snapshots
/dev/sda5 287435776 7617312 278157536 3% /root
/dev/sda5 287435776 7617312 278157536 3% /boot/grub2/i386-pc
tmpfs 4031176 19584 4011592 1% /tmp
/dev/sda5 287435776 7617312 278157536 3% /srv
/dev/sda5 287435776 7617312 278157536 3% /usr/local
/dev/sda5 287435776 7617312 278157536 3% /home
/dev/sda5 287435776 7617312 278157536 3% /opt
/dev/sda5 287435776 7617312 278157536 3% /boot/grub2/x86_64-efi
/dev/sda5 287435776 7617312 278157536 3% /var
/dev/sda1 262144 34584 227560 14% /boot/efi
tmpfs 806232 60 806172 1% /run/user/1000
Once again, my thanks to all for the help and advice provided.