Linux Device Change Breaks Encrypted Swap

Linux disk partition names such as /dev/sda1, /dev/sda2 are not as fixed as they once were. From time to time they can change. Perhaps due to a hardware change or kernel upgrade, or sometimes for no apparent reason. If and when this happens on your system, things can break. In this case, an encrypted swap partition had been configured as “/dev/sda6”, and failed to activate following a change in the /dev/sdXX partition names. This article describes the symptoms and a fix.

The article also discusses a bug affecting Ubuntu 14.04 based distributions, which can make it more difficult to recover an encrypted swap configuration broken by a device name change. Continue reading

Picture Frames and Captions with ImageMagick

This article discusses some of the caption and border effects available with the ImageMagick image processing package. ImageMagick is freely available for Linux and Windows. It offers a huge number of image processing options, so many in fact, that using the program can be a little tricky.

The following examples were evolved from the ImageMagick online documentation, plus a good deal of trial and error to get the details right. I used Linux, but the same commands should work under Windows. Continue reading

Relabel a FAT File System in Linux

The venerable fat16 and fat32 file systems are still in widespread use today. Devices such as digital cameras, satellite navigation systems, memory sticks and mp3 players all make use of FAT

Mount a FAT file system in Linux, and it will appear as something like this:

[root@pluto ~]# df
Filesystem     1K-blocks      Used Available Use% Mounted on
/dev/sdb         7716112   7274796    441316  95% /media/0EB5-6037
/dev/sdc1       15549952  14225152   1324800  92% /media/1FC3-3137

Those hex numbers on the left are the default volume labels, and pretty unfriendly they are. The two entries above actually correspond to an MP3 player (Sansa Clip+) and the player’s expansion SD card. I used mlable to allocate more meaningful volume names. Continue reading

Solaris Disk EFI Headers

“format” is the Solaris tool used to initialize disks. Format can sometimes have a problem with disks that bear an EFI disk label. In which case, replacing the EFI label with a more traditional VTOC disk label can help.

The problem appears when an attempt is made to label the disk using format. The label operation fails with “Current disk is unformatted”. Many other format options fail with the same message. Newfs will not recognise the disk and it is therefore impossible to create a file system. Continue reading