A 2ed hard drive is not completely blank

I see the file lost+found on the hard drive it's locked out and has an X. Is this where the gray space piggy is? If so, can that be accessed and deleted?

For diagnostic purposes, what is the output of the commands

uname -a
lsb_release -crid
sudo fdisk -l

Do you see the file system in Nautilus

Yes, I see it. it's right under computer on the right when I open files and can move files onto it and it boots at startup. So I got that right. :)
  I just don't understand what so much space is going to waste. showing "gray" on the property of it.
I understand why ram never show up as all of what you truly have. But really space on a hard drive doing nothing? I'm lost.

Here is the readout

unname -a
Linux hermann 4.4.0-104-generic #127-Ubuntu SMP Mon Dec 11 12:16:42 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

lsb_release -crid
Distributor ID: Ubuntu
Description: Ubuntu 16.04.3 LTS
Release: 16.04
Codename: xenial

sudo fdisk -l
Disk /dev/sda: 149.1 GiB, 160041885696 bytes, 312581808 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x000ef868

Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 306311167 306309120 146.1G 83 Linux
/dev/sda2 306313214 312580095 6266882 3G 5 Extended
/dev/sda5 306313216 312580095 6266880 3G 82 Linux swap / Solaris

Disk /dev/sdb: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
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: dos
Disk identifier: 0x0053cfbf

Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 1953523711 1953521664 931.5G 83 Linux

Is that "grey" "unusable" area at the beginning or at the end of the picture of the disk?

Also, what is the output of:

mount

Thanks

 mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,nosuid,relatime,size=2969208k,nr_inodes=742302,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=597924k,mode=755)
/dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
tmpfs on /sys/fs/cgroup type tmpfs (rw,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb,release_agent=/run/cgmanager/agents/cgm-release-agent.hugetlb)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event,release_agent=/run/cgmanager/agents/cgm-release-agent.perf_event)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset,clone_children)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids,release_agent=/run/cgmanager/agents/cgm-release-agent.pids)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=30,pgrp=1,timeout=0,minproto=5,maxproto=5,direct)
mqueue on /dev/mqueue type mqueue (rw,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,relatime)
cgmfs on /run/cgmanager/fs type tmpfs (rw,relatime,size=100k,mode=755)
tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=597924k,mode=700,uid=1000,gid=1000)
gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000)

OK I found this page.
https://askubuntu.com/questions/573211/what-does-the-grey-slice-in-disk-usage-represent

It explains the why.
By default ext2, ext3 and ext4 reserve 5% of all space for the root user and to prevent fragmentation.

My plan is to move all my files to it, then do a fresh install of Linux after 12 years of just updating, it's time to do a fresh install.
 Then I want to leave all my music, photo and video files on it. there is a lot of it too. around 750BM. and they are all in separate files like. music/band/ then all there albums for that band and so on for each band. same with videos and photos.

so do I really need that much space for that? or is 1% as the page shows or 2% going to be enough?? to prevent fragmentation? I really don't know what the size of the info is for preventing fragmentation? and would hate to undercut myself.

I think you need not worry.
If I interpret your data correctly, you currently have an Ubuntu partition of 146.1G size.
What is the site of your music, photo and video collection - 750 MB or 750 GB?
In any case, both with 5% and with 1% space reserved for root there will be enough space left on the new disk.
And as long as your disk is not (almost) full, you will not see a difference with the two different limits.

Cool, thanks for the info.