raid – Ubuntu 18.04, 1.5G Swap 100% used (32G RAM), soft RAID1. How to increase SWAP size?

I have a production server, recently, I have seen server becomes slow sometimes, and SSH is slow, and once get into the terminal, even press ENTER is slow.

When the server is OK, I checked the memory usage and CPU, CPU looks fine, RAM looks fine except SWAP is 100% used. I googled it seems SWAP should not be 100% used, maybe 50%.

So I would like to increase the SWAP size. But since this is a production server, and it has soft RAID1 configured, so I don’t want to mess it up until I am sure it is absolutely correct.

Here are the server configs:

CPU is E3-1245-V2, 32G RAM, 3x2T HDD

top command result:

top - 05:33:54 up 2 days, 13:45,  1 user,  load average: 2.43, 2.43, 2.50
Tasks: 243 total,   1 running, 165 sleeping,   0 stopped,   0 zombie
%Cpu(s): 28.4 us,  0.6 sy,  0.0 ni, 69.0 id,  1.7 wa,  0.0 hi,  0.2 si,  0.0 st
KiB Mem : 32893852 total,   278960 free, 28153624 used,  4461268 buff/cache
KiB Swap:  1569780 total,        0 free,  1569780 used.  4226648 avail Mem 

df -h result:

Filesystem      Size  Used Avail Use% Mounted on
udev             16G     0   16G   0% /dev
tmpfs           3.2G  1.5M  3.2G   1% /run
/dev/md3         20G  7.4G   11G  41% /
tmpfs            16G     0   16G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs            16G     0   16G   0% /sys/fs/cgroup
/dev/md2        487M  148M  310M  33% /boot
/dev/md4        1.8T  536G  1.2T  32% /home
tmpfs           3.2G     0  3.2G   0% /run/user/1000

cat /proc/mdstat result:

Personalities : (raid1) (raid0) (raid6) (raid5) (raid4) (linear) (multipath) (raid10) 
md4 : active raid1 sdb4(1) sdc4(2) sda4(0)
      1931981760 blocks (3/3) (UUU)
      bitmap: 5/15 pages (20KB), 65536KB chunk

md2 : active raid1 sda2(0) sdb2(1) sdc2(2)
      523200 blocks (3/3) (UUU)
md3 : active raid1 sda3(0) sdb3(1) sdc3(2)
      20478912 blocks (3/3) (UUU)
unused devices: <none>

sudo swapon --show result:

/dev/sdb5 partition 511M 511M   -2
/dev/sdc5 partition 511M 511M   -3
/dev/sda5 partition 511M 511M   -4

I was going to follow this tutorial but I am afraid since I have soft raid1 here, I am not sure if the instructions above still apply, or it should work.