Re: [gentoo-user] About interpreting output of df -h

[Indexer]

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On 03/12/2010, at 08:23, Harry Putnam wrote:

> Can anyone tell me how determine what these kind of useless names
> really mean?
>
> From df -h
> Filesystem            Size  Used Avail Use% Mounted on
> rootfs                1.9G  283M  1.6G  15% /
> /dev/root             1.9G  283M  1.6G  15% /
>
> How are you supposed to tell what actual device these things are on.

rootfs is a symlink to the device

william@Xerxes / $ ls -al /dev/root 
lrwxrwxrwx 1 root root 4 Oct 31 18:26 /dev/root -> sda3
william@Xerxes / $ df -h
Filesystem            Size  Used Avail Use% Mounted on
rootfs                829G  803G   27G  97% /
/dev/root             829G  803G   27G  97% /
rc-svcdir             1.0M  132K  892K  13% /lib64/rc/init.d
udev                   10M  304K  9.8M   3% /dev
shm                   3.0G   24K  3.0G   1% /dev/shm
/dev/sdb2             250G  234G   17G  94% /mnt/larry.1
/dev/sdb3             682G  614G   68G  91% /mnt/larry.2
/dev/sda1              31M   26M  3.3M  89% /boot
william@Xerxes / $ 

for example, when using UUID devices, the same is true

william@Xerxes / $ ls -al /dev/disk/by-uuid/
total 0
drwxr-xr-x 2 root root 160 Nov 27 10:35 .
drwxr-xr-x 6 root root 120 Nov  5 00:10 ..
lrwxrwxrwx 1 root root  10 Oct 31 18:26 42f0c22c-dde5-4fbb-9d79-158b14d1faf8 -> ../../sdb2
lrwxrwxrwx 1 root root  10 Oct 31 18:26 7ca26cca-04aa-4fe7-8b1b-5d9b059648a0 -> ../../sda1
lrwxrwxrwx 1 root root  10 Oct 31 18:26 8a444308-a234-4c97-bd91-6e4ead0c5273 -> ../../sda3
lrwxrwxrwx 1 root root  10 Oct 31 18:26 b5af92b2-0e55-4b08-9c7f-ff2124c53921 -> ../../sdb1
lrwxrwxrwx 1 root root  10 Oct 31 18:26 cc02ce4e-3761-4084-ba82-d78b0c2cb636 -> ../../sda2
lrwxrwxrwx 1 root root  10 Oct 31 18:26 edf30a91-be1a-47ce-9c4a-d6ad89f94ee9 -> ../../sdb3
william@Xerxes / $ 

They are all just symlinks that are generated by udev.


>
> I know I can look in fstab... but that is something of a crap shoot
> since it is user configured.

So? It should not be touchable by human hands unless they have root. The only way this would change is if someone changed it, and you can easily track who with sudo and modification times etc. 

>
> So what commands will show real devices not makebelieve baloney, and
> allow me to see the usage devices are put to?

Next time ask nicely. What is so hard about saying "Im a bit lost, how do i find the device that this points to". 

>
> Why do we use these kind of names anyway?

It allows for dynamic configurations of things, and some other voodoo that can be done. For example, you can if using UUID's move all your disks in their sata ports, and not affect your system's mounts because root will point at the device as listed in the UUID section.

>
> fdisk yes,  but you can't tell what usage the devices are put to with that.
>
>
>

William Brown

pgp.mit.edu



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