How to copy large files, when Puppy Linux is on a USB drive.

[bigpup]

Typical 4GB RAM computer. Less RAM available is even more of an issue.
Trying to copy large files (larger than 3GB), to location in the operating file system of Puppy Linux OS, when running from install on a USB drive.
Unless you have a lot of memory (8GB or more).
You will probably get this error:
'no space available....' after copying certain amount of data.

Why this error?
Puppy Linux OS, installed on a USB, is running in PUPMODE 13.
In this pupmode, it is using a save ramdisk (space in RAM) to store stuff that goes into the pup save file/folder.
Until the save is updated, by clearing out stuff in the save ramdisk, by writing to the save using the save desktop icon, auto write time period, or shutdown.
The save ramdisk can become full, using all the available free ram.

When butting very large files on the Puppy OS running from a USB.
Copy it to /initrd/pup_ro1/ which is directly writing to the save file/folder.
Also can copy it to /mnt/home which is outside of the save, on the top layer of the partition, outside of the operating file system.

Note:
Pupmode 13 operation does clear out save ramdik, if ram is getting too low of free space, but it will not do it as you try to put something into the save ramdisk.
It works more like, you start a program and it sees the save ramdisk is using needed ram space, to be able to run the program.

[williams2]

If you have 4G of ram, it's probably got a little less than 4G of ram. Especially if you have an onboard video card, that is taking ram for it's own use, maybe 400MB or 500MB.

Puppy usually copies it's sfs file to a tmpfs ram drive, which uses ram, maybe another 400G or 500G or more, ram that can not be released. You can boot pfix=nocopy if that 300 or 400 or 500MB would make a difference.

Puppy will automatically mount a file system in ram that is limited to about 1/2 of your ram, which for a computer with what free tells me is 3.5G, is about size=1812800k (about 1.8G)

You can remount the tmpfs file system with a larger limit (the number is just a limit, not actual size.)
Like this:

mount-FULL -o remount,size=32G devtmpfs /dev

Which sets a limit of 32G. You don't need to actually have 32G, it's just a limit.

If you use dd to copy a large file, directly to a mounted drive, it should not use much ram, as seen in htop. And cp -a or rsync -a

dd if= of= bs=1M

The mega Firefox plugin seems to download completely to ram, then copies it to a file system.
In which case I can create a swap file.

EDIT: fixed typos.

[wiak]

400G or 500G or more, ram that can not be released.

You must have a lot of RAM!, but clearly a typo.