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Old 05-02-2015, 04:14 PM   #1
tearsforhari
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What is the /dev/mapper partition on Ubuntu 12.05.4 and how did I install it?


I am running two linux web-servers. One I am just setting up. On the other, I noted the following partition:
Code:
>df -h
Filesystem                      Size  Used Avail Use Mounted on
/dev/mapper/Machinename-root     27G  4.1G   21G  17 /
udev                            996M   12K  996M   1 /dev
tmpfs                           202M  792K  201M   1% /run
none                            5.0M     0  5.0M   0% /run/lock
none                           1006M  224K 1006M   1% /run/shm
/dev/sda1                       228M   90M  126M  42% /boot
/home/Amy/.Private               27G  4.1G   21G  17% /home/Amy
But on the one that I am installing, so far I get this:
Code:
>df -h
Filesystem              Size  Used Avail Use% Mounted on
udev                    996M   12K  996M   1% /dev
tmpfs                   202M  792K  201M   1% /run
none                    5.0M     0  5.0M   0% /run/lock
none                   1006M  224K 1006M   1% /run/shm
/dev/sda1               228M   90M  126M  42% /boot
How did I get /dev/mapper partition?

Last edited by tearsforhari; 05-02-2015 at 10:02 PM.
 
Old 05-02-2015, 09:53 PM   #2
syg00
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First things first - use [code] tags for output, not [quote] - that way the layout is preserved. Much easier to read for the rest of us trying to help.

/dev/mapper like that generally means LVM. And strictly speaking it isn't a partition but a lv - one of the advantages of LVM is to allow several filesystems on a single partition. As well as allowing growth across several partitions.
The terminology becomes blurred sometimes, but important.
 
Old 05-02-2015, 10:16 PM   #3
tearsforhari
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Ok, changed quote to code. Thanks

1. So, where did the LV come from on the first machine? I don't remember installing anything but the desktop and apache2. I don't see a similar LV on the Ubuntu system I just installed.

2. So, if I wanted to change the disk space allocated to the /dev/mapper/Machine-root (directory?) or volume, how would I go about it? I assume that changing a partition size and a LV are treated differently.

3. I'm asking because on a third machine that runs a Windows Server with Ubuntu running on HyperV, I have a similar /dev/mapper/Machine-root volume or partition (not sure which it is in this case) that is running out of allocated space. I want to practice changing the size of the LV or partition on my test machines before I actually do it on the machine with my data on it. I read about using the resize2fs command.

Last edited by tearsforhari; 05-02-2015 at 10:32 PM.
 
Old 05-02-2015, 10:32 PM   #4
syg00
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Using LVM is an installer option - some distros (particularly server installs) default to using it.
Expanding filesystems is what LVM was made for. Redhat have a beaut LVM admin guide - read that. here is a link to the latest online version. You may be better off with the RHEL 6 version as RH tend to use lots of latest features (in LVM especially) you may not have.
 
Old 05-02-2015, 10:39 PM   #5
tearsforhari
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Yes, I probably installed the Ubuntu server version on the first machine and then added the desktop. On the second machine, I installed the Ubuntu desktop and added apache2.

I'll do some reading...
 
  


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