Raw device not seen after reboot the server

Question

hi,
I hv upgrade kernal in linux 7.2 but when reboot system no raw device found
how can find out raw device

Answer 1

From http://www.fors.com/orasupp/unix/37914_1.HTM
Raw Devices and Oracle - 20 Common Questions and Answers
2. How can a raw device be recognised?
In the /dev directory, there are essentially two type of files: block
special and character special. Block special files are used when data is
transferred to or from a device in fixed size amounts (blocks), whereas
character special files are used when data is transferred in varying
size amounts. Raw devices use character special files; a long listing
of the /dev directory shows them with a 'c' at the leftmost position of
the permissions field, e.g.
crw-rw-rw- 1 root system 15, 0 Mar 12 09:45 rfd0
In addition, character special files usually have names beginning with
an 'r', as shown in the above example. Some devices, principally disks,
have both a block special device and a character special device
associated with them; for the floppy diskette shown above, there is also
a device
brw-rw-rw- 1 root system 15, 0 Apr 16 15:42 /dev/fd0
So the presence of a 'c' in a device does NOT necessarily mean this is a
raw device suitable for use by Oracle (or another application).
Generally, a raw device needs to be created and set aside for Oracle (or
whatever application is going to use it) when the UNIX system is set
up - therefore, this needs to be done with close co-operation between
the DBA and UNIX system administrator.
Once a raw device is in use by Oracle, it must be owned by the oracle
account, and may be identified in this way.