Need information

[Gk Gk]

Ok, I have found this mapping on the server:
--
/dev/mapper/live-rw is mounted on '/' root file system. But the device
underneath the live-rw is a loop device..

# lsblk
NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop0             7:0    0    15G  0 loop
└─live-rw       253:1    0    15G  0 dm   /

So it is a loop device that is mapped to a live-rw device. This loop device
contains this image:

# losetup --list
NAME       SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE
DIO LOG-SEC
/dev/loop0         0      0         0  0 /run/initramfs/fsimg/rootfs.img
0     512

So its the root filesystem image which is being used as a loop device and
mounted on '/' .

My question is, what is the difference between installing root file system
on to a hard disk like /dev/sda  versus mounting it as a loop device image
? What are the advantages we gain from this
type of implementation ?


Thanks
Kumar

On Thu, Aug 24, 2023 at 8:02 PM Robert Heller <heller at deepsoft.com> wrote:

>
> At Thu, 24 Aug 2023 19:09:03 +0530 "Ubuntu user technical support,? not
> for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:
>
> >
> > Hi,
> >
> > In our servers with Ubuntu OS, the  '/' file system is mounted on a
> device
> > mapper as shown below:
> > ---
> > # df -h
> > Filesystem                 Size  Used Avail Use% Mounted on
> > devtmpfs                   252G     0  252G   0% /dev
> > tmpfs                      252G     0  252G   0% /dev/shm
> > tmpfs                      252G   13G  240G   6% /run
> > /dev/mapper/live-rw         15G   13G  1.8G  88% /
> > --
> >
> > Root file system is not mapped to a hard disk. What exactly  is the
> > 'dev/mapper/live-rw' device ? Does it mean that the root file system is
> in
> > memory instead on a hard disk ?   Please explain
>
> What do you mean by "servers"?  Are these VPS in the cloud somewhere?
>
> There are any number of possibilities -- we need much more info to answer
> your
> question.  *One* possibility is LVM.  *I* use LVM on some of my machines:
>
> sauron% df -h
> Filesystem                             Size  Used Avail Use% Mounted on
> tmpfs                                  769M  2.2M  767M   1% /run
> /dev/mapper/sauron-ubuntu_root          50G   42G  5.1G  90% /
> tmpfs                                  3.8G   32K  3.8G   1% /dev/shm
> tmpfs                                  5.0M  8.0K  5.0M   1% /run/lock
> tmpfs                                  3.8G     0  3.8G   0% /run/qemu
> /dev/mapper/sauron-www                 9.8G  1.2G  8.1G  13% /var/www
> /dev/mapper/sauron-distrocds            79G   68G  7.2G  91% /distrocds
> /dev/mapper/sauron-wine                261M  172M   75M  70% /wineC
> /dev/mapper/sauron-Stuff                21G   17G  3.6G  83% /Stuff
> /dev/mapper/sauron-dvdisos              44G   41G  1.1G  98% /dvdisos
> /dev/mapper/sauron-SourceManagementC5  942M  303M  588M  34%
> /home3/heller/Deepwoods
> /dev/md126                             948M  416M  483M  47% /boot
> /dev/mapper/sauron-extra                50G   31G   16G  67% /extra
> /dev/mapper/sauron-localrepo           868M  1.3M  815M   1%
> /var/www/localrepo
> /dev/mapper/sauron-home                 70G   60G  7.4G  89% /home
> /dev/mapper/sauron-pipinbackup         246G  107G  127G  46% /PipinBackup
>
> gollumm1% df -h
> Filesystem                     Size  Used Avail Use% Mounted on
> udev                           1.9G     0  1.9G   0% /dev
> tmpfs                          374M   25M  350M   7% /run
> /dev/mapper/Gollum_m1-m1_root   30G  7.2G   21G  26% /
> tmpfs                          1.9G     0  1.9G   0% /dev/shm
> tmpfs                          5.0M  4.0K  5.0M   1% /run/lock
> tmpfs                          1.9G     0  1.9G   0% /sys/fs/cgroup
> /dev/nvme0n1p1                 920M   27M  830M   4% /boot
> /dev/mapper/Gollum_m1-mp3s      20G   17G  2.6G  87% /mp3s
> /dev/mapper/Gollum_m1-scratch   40G   37G 1022M  98% /scratch
> /dev/mapper/Gollum_m1-home      37G   17G   18G  49% /home
>
> (LVM is a convientient way of managing disk space with large storage
> media.)
> >
> >
> > Thanks
> > Kumar
> >
>
> --
> Robert Heller             -- Cell: 413-658-7953 GV: 978-633-5364
> Deepwoods Software        -- Custom Software Services
> http://www.deepsoft.com/  -- Linux Administration Services
> heller at deepsoft.com       -- Webhosting Services
>
>
> --
> ubuntu-users mailing list
> ubuntu-users at lists.ubuntu.com
> Modify settings or unsubscribe at:
> https://lists.ubuntu.com/mailman/listinfo/ubuntu-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.ubuntu.com/archives/ubuntu-users/attachments/20230825/9de658d9/attachment.html>