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16

Swap not working on clean 14.04 install using encrypted home

rated 0 times [ 16] [ 0] / answers: 1 / hits: 28450 / 2 Years ago, thu, april 21, 2022, 4:23:31

Update 3:

I decided to reinstall the system from scratch to remove any old cruft lying around since I had been experiencing some other issues after the upgrade aswell. Howver, this issue persisted.

On a clean install, choosing to install using "encrypted home" leads to a broken encrypted swap configuration.

Update 2:

I fixed the partioning order that cfdisk complained about, but he issue persists. The swap is now on /dev/sda6, and I can get it up and running as follows:

~$ sudo mkswap /dev/sda6

Setting up swapspace version 1, size = 7998460 KiB

no label, UUID=18881d0f-d9ec-43be-a23f-0cbd78ea6d22



$sudo nano /etc/crypttab # Update crypttad with new UUID



$ sudo /etc/init.d/cryptdisks reload

 * Stopping remaining crypto disks...

 * cryptswap1 (stopped)...                                               [ OK ] 

 * Starting remaining crypto disks...                                        

 * cryptswap1 (starting)..

 * cryptswap1 (started)...                                               [ OK ] 

$ sudo swapon -a



$ls -l /dev/disk/by-uuid/

total 0

lrwxrwxrwx 1 root root 10 May 11 09:04 08b07f88-6da5-4b40-b062-42b3bb1c5f00 -> ../../sda3

lrwxrwxrwx 1 root root 10 May 11 09:08 18881d0f-d9ec-43be-a23f-0cbd78ea6d22 -> ../../sda6

lrwxrwxrwx 1 root root 10 May 11 09:04 19aa372c-05c8-4226-8f09-c54e5566e816 -> ../../sda5

lrwxrwxrwx 1 root root 10 May 11 09:04 A800B16E00B143DA -> ../../sda1

lrwxrwxrwx 1 root root 10 May 11 09:04 D28230E68230D129 -> ../../sda2

lrwxrwxrwx 1 root root 10 May 11 09:08 fcc8c419-8fec-4d4d-b55e-9e4c3b04d21d -> ../../dm-0

But after a reboot swap fails to activate and it once again looks like this:

$ ls -l /dev/disk/by-uuid/

total 0

lrwxrwxrwx 1 root root 10 May 11 09:12 08b07f88-6da5-4b40-b062-42b3bb1c5f00 -> ../../sda3

lrwxrwxrwx 1 root root 10 May 11 09:12 19aa372c-05c8-4226-8f09-c54e5566e816 -> ../../sda5

lrwxrwxrwx 1 root root 10 May 11 09:12 A800B16E00B143DA -> ../../sda1

lrwxrwxrwx 1 root root 10 May 11 09:12 D28230E68230D129 -> ../../sda2

My guess at the moment is that when setting up the disk as being encrypted linux no longer recognizes the partition type and therefore doesn't load it properly causing it to not register for it's UUID and therefore cryptswap can't find it causing the failure. But I don't know how to fix it..

Updated question:

Further testing revealed that I could get the swap up and running by running
$ mkswap /dev/sda5

and then updating /etc/crypttab with the correct UUID and following the steps outlined here:
How do I setup an encrypted swap file?

The problem however remains when I reboot the computer, the /dev/sda5 doesn't appear when I run

$ ls -l /dev/disk/by-uuid/

If I do:

$ cfdisk /dev/sda

I get the following error:

FATAL ERROR: Bad logical partition 6: enlarged logical partitions overlap

                      Press any key to exit cfdisk

The graphical "Disks" utility doesn't complain about any error when opening the disk using it.

$ sudo fdisk -l



Disk /dev/sda: 256.1 GB, 256060514304 bytes

255 heads, 63 sectors/track, 31130 cylinders, total 500118192 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x619aebf1



   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *        2048      206847      102400    7  HPFS/NTFS/exFAT

/dev/sda2          206848   100870143    50331648    7  HPFS/NTFS/exFAT

/dev/sda3       191397888   192397311      499712   83  Linux

/dev/sda4       192399358   500117503   153859073    5  Extended

/dev/sda5       484118528   500117503     7999488   82  Linux swap / Solaris

/dev/sda6       192399360   484118527   145859584   83  Linux



Partition table entries are not in disk order

Original question:

After upgrading to 14.04 (from 13.04) my computer has been experiencing severe slowdowns, when running top i noticed kswap0 taking up alot of cpu time. I also noticed that I didn't have any swap space!

$ sudo swapon -a

swapon: /dev/mapper/cryptswap1: stat failed: No such file or directory

There seems to be some problem with my encrypted swap setup (didn't even know that I had one)

$ cat /etc/crypttab 

cryptswap1 UUID=abe3c568-c8fd-4dfb-b8e9-0520d442dd61 /dev/urandom swap,cipher=aes-cbc-essiv:sha256



$ ls -l /dev/disk/by-uuid/

total 0

lrwxrwxrwx 1 root root 10 May  6 11:00 08b07f88-6da5-4b40-b062-42b3bb1c5f00 -> ../../sda3

lrwxrwxrwx 1 root root 10 May  6 11:00 19aa372c-05c8-4226-8f09-c54e5566e816 -> ../../sda6

lrwxrwxrwx 1 root root 10 May  6 11:00 A800B16E00B143DA -> ../../sda1

lrwxrwxrwx 1 root root 10 May  6 11:00 D28230E68230D129 -> ../../sda2

And looking at my fstab

$ cat /etc/fstab

# /etc/fstab: static file system information.

#

# Use 'blkid' to print the universally unique identifier for a

# device; this may be used with UUID= as a more robust way to name devices

# that works even if disks are added and removed. See fstab(5).

#

# <file system> <mount point>   <type>  <options>       <dump>  <pass>

# / was on /dev/sda6 during installation

UUID=19aa372c-05c8-4226-8f09-c54e5566e816 /               ext4    errors=remount-ro 0       1

# /boot was on /dev/sda3 during installation

UUID=08b07f88-6da5-4b40-b062-42b3bb1c5f00 /boot           ext2    defaults        0       2

# swap was on /dev/sda5 during installation

#UUID=abe3c568-c8fd-4dfb-b8e9-0520d442dd61 none            swap    sw              0       0

/dev/mapper/cryptswap1 none swap sw 0 0

My guess is that there is something wrong the the setup of sda5, but I don't know how to fix it since it is setup up to be encrypted. Would appreciate some help as how to proceed.

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llael

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1 Year ago

answered 2 Years ago elopingapo · Accepted Answer

Known Bug

There is a bug (see below) that overwrites the UUID for the partition as soon as data is written to it. Therefore, you cannot use the UUID to reference the partition to use for encrypted swap.

These days, swap space is hardly ever used. On my machine, swap is only used when I open my 40th tab. When I have no swap, suddenly my computer starts lagging and the browser closes itself. Or in the case of the Chromium browser, a lot of tabs will suddenly 'die'.

For this reason, referencing /dev/disk/by-uuid/ in your /etc/crypttab might seem to be working for a while, but as soon as your swap space is actually used, it will overwrite the UUID because the entire partition is used for encrypted data storage.

Easy Fix

The easy fix is to reference the swap partition by device in your /etc/crypttab, e.g.:

cryptswap1 /dev/sda5 /dev/urandom swap,cipher=aes-cbc-essiv:sha256

Warning: this is probably safe on a laptop (I use it like this), but if you are on a desktop with swappable drives or have other reasons for changing the drive/partition layout, you don't want to do this, as a normal storage partition might suddenly be used for swap.

Note: You need to reboot for this change to take effect, because only when booting will /dev/mapper/cryptswap1 be created.

Proper Fix

The proper way to fix this is to make sure the part of the raw partition that stores the UUID is not overwritten by encrypted swap data, so it will still be there on reboot. However, I'm not sure where the UUID is written and how much bytes it takes up. You could, at your own risk, test it like so:

cryptswap1 UUID=abe3c568-c8fd-4dfb-b8e9-0520d442dd61 /dev/urandom swap,offset=36,cipher=aes-cbc-essiv:sha256

Note the offset=36.

Please if you have an Ubuntu One account log in and go to Bug #1310058 on Launchpad and choose (or click here): "This bug affects me too" so the bug will gain 'popularity' and is more prone to get fixed.

Update 2014-10-27

I also stumbled upon this. Not verified by me. It looks like offset trick with more verbosity and comments about rebuilding a broken swap.

https://bugs.launchpad.net/ubuntu/+source/ecryptfs-utils/+bug/1310058/comments/22