Linksys1900acs low storage space

[titanium_akt]

I'm trying to use Passwall2 and OpenVPN server on a Linksys1900acs. While Passwall takes huge space (xray file 25MB) there are no more space left for proper installation of OpenVPN.

Collected errors:
 * verify_pkg_installable: Only have 52kb available on filesystem /overlay, pkg e2fsprogs needs 192
 * opkg_install_cmd: Cannot install package resize2fs.

root@OpenWrt:~# df -h
Filesystem                Size      Used Available Use% Mounted on
/dev/root                 3.3M      3.3M         0 100% /rom
tmpfs                   248.0M      1.0M    247.0M   0% /tmp
/dev/ubi0_1              23.0M     21.7M     32.0K 100% /overlay
overlayfs:/overlay       23.0M     21.7M     32.0K 100% /
tmpfs                   512.0K         0    512.0K   0% /dev

What is that huge tmpfs? If it is ram why is it half the size of device ram (512)?
How is that having 128MB of flash size I cannot install these two together?
Should I use a memory stick to increase root size?
Apparently these devices have two main partitions for two firmwares one as backup. Is there any way to merge those two to form a one bigger partition without a backup OS?
Regards

[frollic]

@titanium_akt

What is that huge tmpfs? If it is ram why is it half the size of device ram (512)?

yes
it's the way it's been designed, you can shrink it if you build your own image.

@titanium_akt

Should I use a memory stick to increase root size?

yes, extroot will work for this.

@titanium_akt

Is there any way to merge those two to form a one bigger partition without a backup OS?

probably, AFAIK it's never been done.

[titanium_akt]

Thanks,
Attached a memory stick and now I have plenty of storage space. Hope the device treats memory stick well enough to make it last through years.