06-23-2013
Basically, for all *NIX systems, filesystems are created and used via block devices, not character devices.
By definition, character devices have a window of 1 char - a driver might buffer that a little bit (so you can unchar(), or back up one byte.
Block devices are, by definition - finite in size (while char devices may be infinite) - and block devices are "seekable". Because they are seekable, an information system, such as a file system can be stored on them.
Note: some device drivers use ioctl() to perform actions similar to seek - hence the confusion. However, the original definition (at least as far back as UNIX v6) was that character devices did not seek.
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LEARN ABOUT OPENSOLARIS
devid_cache
devices(4) File Formats devices(4)
NAME
devices, devid_cache, snapshot_cache, mdi_scsi_vhci_cache, mdi_ib_cache, devname_cache - device configuration information
SYNOPSIS
/etc/devices
/etc/devices/devid_cache
/etc/devices/snapshot_cache
/etc/devices/mdi_scsi_vhci_cache
/etc/devices/mdi_ib_cache
/etc/devices/devname_cache
DESCRIPTION
The directory /etc/devices is a repository of device-related data. Files in this directory are used to preserve this information across
reboots and are created and updated as necessary by the system.
There are no administrative actions necessary with respect to files in /etc/devices. Should the contents of a file become corrupted or an
update fail, the file can simply be removed. The system re-creates the file as necessary.
SEE ALSO
devfsadm(1M), dev(7FS), ddi_devid_compare(9F), ddi_devid_compare(9F)
NOTES
Files in this directory do not constitute an API. Files might not exist or might have a different content or interpretation in a future
release. The existence of this notice does not imply that any other documentation that lacks this notice constitutes an API.
SunOS 5.11 8 Jun 2006 devices(4)