Raw partitions on linux

Im trying to set up sybase on suse 6.3 and can't specify a raw partition for master.dat. I can specify the block device i.e. /dev/hdb6 but it really wants a character device. I can see devices called raw* but I dont know what they relate to also a man of raw gives me a command that will set up character devices but I don't have the command only the man page.

Any help appreciated
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Try "/dev/rhdbX".. ("X" is your raw partition number.......If the device does not exist do a
"mknod c /dev/rhdbX <maj> <min>".......where "X" is your raw partition number...where <maj> is the device major number....and <min> is the device minor number....<maj> and <min> will be the same for both "hdbX" and "rhdbX"....use "fdisk /dev/hdb" and create the partition "/dev/hdbX".....
Just one more thing..... Which version of Sybase are you configuring.....you might want to cheak the Sybase document to see if raw devices are supported...
orangoAuthor Commented:
I have set up the devices as you suggested the syntax didn't work until I moved the c after the device.
This gave me an ls -al of
brw-rw----   1 sybase   disk       3,  69 Dec  6 22:26 /dev/hdb5
brw-rw----   1 sybase   disk       3,  70 Dec  6 22:26 /dev/hdb6
brw-rw----   1 sybase   disk       3,  72 Dec  6 22:26 /dev/hdb8
brw-rw----   1 sybase   disk       3,  73 Dec  6 22:26 /dev/hdb9
crw-r--r--   1 sybase   root       3,  69 Feb 11 10:11 /dev/rhdb5
crw-r--r--   1 sybase   root       3,  70 Feb 11 10:14 /dev/rhdb6
crw-r--r--   1 sybase   root       3,  72 Feb 11 10:14 /dev/rhdb8
crw-r--r--   1 sybase   root       3,  73 Feb 11 10:14 /dev/rhdb9

but when I tried to specify /dev/rhdb5 as the master device it returns
cannot open file '/dev/rhdb5' Operating system returned :Input/output error.

I have tried changing the permissions to 660 (also tried 777) and the group to "disk" like /dev/hdb5 but it still gives the same error.

Thanks for your help.

Also the sybase version is and when you specify a block device it warns you and says it really wants a raw/character device so writes are performed without buffering.
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orangoAuthor Commented:
Adjusted points to 300
orangoAuthor Commented:
see text above.
(sorry added it as a comment)
I supect that RAW support is planned in Linux, but it's not yet a reality.

I quote SuSE ( http://sdb.suse.de/sdb/en/html/adabas_raw_device.html )

You want Adabas D to store its data directly onto a raw device instead of a file. However xcontrol only returns with an error message upon this request. This
is caused by the Linux Kernel, which has no driver for a raw device. However there exists a buffered block device.

orangoAuthor Commented:
Thanks for the help. I had read in a raid howto on the web that raw devices were not supported yet but didn't know how old the howto was and finding the raw man page I thought I was in with a chance.

Next question is can I give chander and tosi 150 points each ?
you might want to have a look at the TiVO sources which _do_ support raw devices...
I have not seen 'charaster' devices for disk in /usr/src/linux/Documentation/devices.txt
Community Support has reduced points from 300 to 100
Reducing points to allow points to be split among experts.

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There's raw device support in FreeBSD, and the application can happily run under amulation, even better - since FreeBSD has better VM subsystem.
Give it a try.
I'll post it as an answer; there is
a RAW io support available - from
Silicon Graphics Inc.:
Use with care.
I still think that FreeBSD is better.

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According to SuSE's announcement of SuSE 6.4, they already support raw IO devices ( disks ) from April 4:th. That should make many a man happy :-)
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