Gentoo Archives: gentoo-user

From: Mick <michaelkintzios@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Running out of space on /var partition
Date: Mon, 25 Jul 2011 11:41:08
Message-Id: 201107251240.04670.michaelkintzios@gmail.com
In Reply to: Re: [gentoo-user] Running out of space on /var partition by YoYo Siska
1 On Monday 25 Jul 2011 12:18:34 YoYo Siska wrote:
2 > On Mon, Jul 25, 2011 at 11:40:55AM +0100, Mick wrote:
3
4 > > I never understood properly how the mount --bind/rbind works. I
5 > > understand that the original partition content becomes visible on a
6 > > second partition, but I'm not at all sure what happens when the space on
7 > > the first partition runs out?
8 >
9 > Not "on a second partition" but under another "mount point" i.e. another
10 > path... When you try to access a file by its filename, the kernel takes
11 > the absolute file name, compares it to all the moutend "mount points",
12 > takes the best match and tries to find (create) the file in that
13 > filesystem/partition...
14 >
15 > Lets say you do something like:
16 >
17 > mount /dev/sda1 / (well... you don't actually do this... ;)
18 > mount /dev/sda2 /mnt/sda2
19 > mount --bind /mnt/sda2/bigtmp /tmp
20 >
21 > Then path "/home/yoyo/something" is accessing file "home/yoyo/something"
22 > on partition sda1.
23 >
24 > The path "/mnt/sda2/somedir/somefile" is accessing file "somedir/somefile"
25 > on partion sda2.
26 >
27 > The path "/tmp/somedir/somefile" is accessing file
28 > "bigtmp/somdir/somefile" on partition sda2.
29 >
30 >
31 > The files (and free space) under /mnt/sda2 and /tmp are actually on
32 > partition sda2, everything else is on sda1...
33 >
34 >
35 > So if sda1 runs out of space (by writing to other places than /mnt/sda2
36 > and /tmp), it doesn't in any any way affect /mnt/sda2 and /tmp which
37 > have their free space from sda2. Conversely if you fill up sda2 by
38 > writing to /tmp, your "system" partition still has free space ;)
39 >
40 >
41 > yoyo
42
43 I think I got it. Thanks!
44 --
45 Regards,
46 Mick

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