I can't get zerofree to work and I've spent hours on this.
I'm running centos6.5 64 bit with zerofree-1.0.3-1, my root partition is /dev/mapper/vg_x2100centos6v-lv_root.
if I try to run zerofree in a normal console I get:
so I sent the machine in runlevel 1 with #init 1 and tried the same command again and I get the same thing (zerofree: filesystem /dev/mapper/vg_x2100centos6v-lv_root is mounted rw).

so (following the instructions here) I then ran:I get stuck here, I cannot get past this 'busy' error.

So I also tried rebooting the machine into runlevel 1 tried again but still the command doesn't work. In runlevel1 zerofree can't see the root partition and mount commands don't work
what do I have to do to get zerofree to run?

how did you install it ?
from a source build ?
http://intgat.tigress.co.uk/rmy/uml/index.html
http://intgat.tigress.co.uk/rmy/uml/zerofree-1.0.3.tgz
or some other way

I installed it from http://repos.zendbox.com/
I would have installed it from zerofree-1.0.3.tgz but I couldn't find any install instructions anywhere.

Usually, there is a README in the tarball that gives instructions about how to install a package.

This article gives a good overview of installing from sources.

http://www.thegeekstuff.com/2012/06/...l-from-source/

I solved this issue: (btw there was no readme in the unpacked zerofree souce file, there was nothing to go on). These steps worked for me, maybe they will help someone with the same problem:
1) make a backup copy of /etc/fstab
2) edit /etc/fstab and change the following 'default' values to 'ro'.3) reboot <-- partitions will now be in read-only
the following was done in a putty console from another pc:
6) # echo "u" > /proc/sysrq-trigger
7) # mount /dev/mapper/your_root_partition/ -o remount,ro
8) # zerofree -v /dev/mapper/your_root_partition
(percentage progress)....
9) # zerofree -v /dev/mapper/your_home_partition
(percentage progress)...
10) restore the root partition back to rw
# mount /dev/mapper/your_root_partition/ -o remount,rw
10a) restore original /etc/fstab from backup copy you made in step 1.
11) check /etc/fstab. make sure it's back to default
12) reboot <--- machine will now boot as normal.

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