Publisher review:Cowloop driver allows block-devices or files to be used in a read-write fashion without modifying the block-device or file itself. The cowloop driver allows block-devices or files to be used in a read-write fashion without modifying the block-device or file itself.
Modified data-blocks are not written back to the original read-only device, instead they are written to a separate file called the copy-on-write file or cowfile.
The cowloop driver offers (default) 16 cowdevices. To every cowdevice a read-only device (file) can be assigned with a corresponding cowfile to store the modifications for that read-only device. The cowloop driver offers various possibilities, such as:
- A filesystem stored on a non-writable medium (on a write-protected floppy, in a file on a cdrom/dvd) can still be mounted read-write via a cowdevice.
- One filesystem can be used as a basis for various independent sessions that can be active in parallel. For each session a separate cowdevice is prepared. Every cowdevice could use the same read-only device (or file) holding the filesystem, while every cowdevice uses a dedicated cowfile holding the specific modifications for that session. Each cowdevice is mounted separately via the cowloop driver and unmounted again after use.
- A database stored in a file or on a block-device can be used read-write without modifying the original contents.
Cowloop driver 3.0 is a C/C++ script for Test and Measurement scripts design by Gerlof Langeveld.
It runs on following operating system: Linux / BSD.
Operating system:Linux / BSD
Cowloop driver 3.0 script details 
