Online Documentation Server
 ПОИСК
ods.com.ua Web
 КАТЕГОРИИ
Home
Programming
Net technology
Unixes
Security
RFC, HOWTO
Web technology
Data bases
Other docs

 


 ПОДПИСКА

 О КОПИРАЙТАХ
Вся предоставленная на этом сервере информация собрана нами из разных источников. Если Вам кажется, что публикация каких-то документов нарушает чьи-либо авторские права, сообщите нам об этом.




Disks without filesystems Next Up Previous Contents Index
Next: Allocating disk space Up: Using Disks and Other Previous: Other tools for the

Disks without filesystems

Not all disks or partitions are used as filesystems. A swap partition, for example, will not have a filesystem on it. Many floppies are used in a tape-drive emulating fashion, so that a tar  or other file is written directly on the raw disk, without a filesystem. Linux boot floppies don't contain a filesystem, only the raw kernel.

Avoiding a filesystem has the advantage of making more of the disk usable, since a filesystem always has some bookkeeping overhead. It also makes the disks more easily compatible with other systems: for example, the tar  file format is the same on all systems, while filesystems are different on most systems. You will quickly get used to disks without filesystems if you need them. Bootable Linux floppies also do not necessarily have a filesystem, although that is also possible.

One reason to use raw disks is to make image copies of them. For instance, if the disk contains a partially damaged filesystem, it is a good idea to make an exact copy of it before trying to fix it, since then you can start again if your fixing breaks things even more. One way to do this is to use dd :

$ dd if=/dev/fd0H1440 of=floppy-image
2880+0 records in
2880+0 records out
$ dd if=floppy-image of=/dev/fd0H1440
2880+0 records in
2880+0 records out
$
The first dd  makes an exact image of the floppy to the file floppy-image , the second one writes the image to the floppy. (The user has presumably switched the floppy before the second command. Otherwise the command pair is of doubtful usefulness.)



Lars Wirzenius
Sat Nov 15 02:32:11 EET 1997


With any suggestions or questions please feel free to contact us