mounted ISO; What determines available room?
Robert Heller
heller at deepsoft.com
Tue Dec 31 01:04:02 UTC 2019
At Mon, 30 Dec 2019 19:14:31 -0500 "Ubuntu user technical support, not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:
>
> Once an ISO file is mounted for use like in an install ISO, what
> factors determine how much room is available?
>
> Example of what I mean with the ubuntu focal fossa 20.4 iso:
>
> inside mounted ISO:
>
> df -h
>
> Filesystem Size Used Avail Use% Mounted on
> udev 2.4G 0 2.4G 0% /dev
> tmpfs 494M 1.1M 493M 1% /run
> /dev/sr0 1.6G 1.6G 0 100% /cdrom
> /dev/loop0 1.5G 1.5G 0 100% /rofs
> /cow 2.5G 104M 2.4G 5% /
> tmpfs 2.5G 16M 2.4G 1% /dev/shm
> tmpfs 5.0M 4.0K 5.0M 1% /run/lock
> tmpfs 2.5G 0 2.5G 0% /sys/fs/cgroup
> tmpfs 2.5G 84K 2.5G 1% /tmp
> tmpfs 494M 8.0K 494M 1% /run/user/999
> tmpfs 494M 0 494M 0% /run/user/0
>
> Notice root shows 5% used and a Size of 2.5G
>
> How would someone making this iso arrange things so that the size was
> 7GB for `/' Or any other size for that matter.
I expect that the init script run as part of the boot process "creates" the
root file system. The tmpfs "filesystems" are a type of ramdisk (I expect
that they are sparse ramdisks, where the "empty" blocks are allocated from
virtual memory as they are allocated).
The root file system is probably something a squashfs or created from a
squashfs. You will need to look at the init ramdisk file, located somewhere
under /cdrom for the exact code...
>
>
>
--
Robert Heller -- 978-544-6933 Cell: 413-658-7953
Deepwoods Software -- Custom Software Services
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