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Hibernation with LVM, LUKS and a Swapfile

With this How To you can use a swapfile instead a swap partition as described here: http://slackware.osuosl.org/slackware-14.0/README_CRYPT.TXT

First create a swapfile: (you can choose another name and / or size if you want)

dd if=/dev/zero of=/swapfile bs=1M count=4096
mkswap /swapfile 

Activate the Swap:

swapon /swapfile

Check if the Swapfile is recognized by the system:

cat /proc/swaps 
Filename                                Type            Size    Used    Priority
/swapfile                               file            4194300 0       -1

Add to the fstab

/swapfile        none             swap        defaults         0   0

For suspend/resume you need to append 2 kernel Parameter in /etc/lilo.conf resume and resume_offset.

resume is the partition where the swapfile is located (e.g /dev/sda, /dev/cryptslack/root) resume_offset is the beginning of the swapfile on the resume partition, you can get the offset with

sudo /sbin/filefrag -v /swapfile | head -n -3 | tail -n 1 | awk ' {print $3 }'

your lilo entry should look like this:

# Append any additional kernel parameters:
 append="vt.default_utf8=1 resume=/dev/cryptslack/root resume_offset=1134591"

You need to patch the initrd to recognize the resume_offset parameter

mkdir patched_initrd
cd patched_initrd
cp -r /boot/initrd-tree .
echo "1134591" > resoffset
patch < init-swapfile.patch

after successfull patching ,pack the initrd to /boot/initrd-swapfile.gz

find . -print0 | cpio -ov -0 --format=newc | gzip -9 > /boot/initrd-swapfile.gz
i recommend you to test this initrd first with another bootentry
image = /boot/vmlinuz
initrd = /boot/initrd-swapfile.gz
root = /dev/cryptslack/root
label = "Linux Swapfile"

then you need to run lilo to save the changes


after a reboot you can suspend to your swapfile as with your swap partition

you need the reboot, suspend also uses resume_offset to find the swapfile


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