I used the free -h
command to show the available RAM in the live image of Lubuntu loaded into RAM .
If I created it by the command: dd if=lubuntu-19.04-desktop-amd64.iso of=/dev/sdb bs=512k
, then I get my actual total ram.
But if I created the live-usb using MKusb, I get about 1gb less of ram ... I'm using Mkusb to make a persistent live usb.
General description of what is happening
As noted in comments, 19.04 has passed the end of life date, so I think we should test not only that version but also another version (that is still supported).
Cloned USB boot drives made with
dd
,mkusb
and any other cloning tool will be identical. If there is a difference, it is not a cloning tool, or there is some write error (maybe due to faulty hardware). The block size selected bydd
withbs
can change the speed of cloning, but does not change the result of the cloning.According to my experience, Ubuntu live (live-only) systems allocate approximately half of the available RAM to the root file system
/
A persistent live drive made with
mkusb
version 12 aliasmkusb-dus
uses an overlay method, where the size of the partition for persistence decides the size of the root file system.So when the partition for persistence is
greater than half of the RAM, the root file system will increase compared to a live system,
smaller than half of the RAM, the root file system will decrease compared to a live system.
The amount of RAM for other purposes (which is free before it is used by the programs, that you start) will depend on how much that is used for the overlay system. The following test results describe what happens in different cases.
Test results
I found no unexpected behaviour when testing Lubuntu 19.04. For that reason I am rather sure that those results can also represent Lubuntu 18.04.x LTS.
I also tested Lubuntu 19.10, which has a modified mechanism in the package
casper
, and can be expected to behave in a different way. These results should also represent Focal Fossa to be released as Lubuntu 20.04 LTS.Summary
The main difference is the free memory in case #3 in both versions (19.04 and 19.10), and the reason is that the boot option
toram
was used in that case. It means that the [whole] image of the iso file is copied to RAM. Otherwise there is no significant difference in the usage of RAM.Details
Explanation of the list above:
a persistent live drive made with mkusb (and 67% selected for persistence)
the remaining part of the list is output from
free -h
Shellscript
The following shellscript was used to collect data from each of the run case.
The following output lists can be used by you, if you want to compare your results with mine in order to discuss differences.
Output for Lubuntu 19.04
Output for Lubuntu 19.10