RAW devices are not stable

ksushants · 10-12-2012, 09:23 AM

Hi all,

We have created raw devices on the "SUSE Linux Enterprise Server 11 SP2 (x86_64)". these raw devices are used for informix database and to have different owner(i.e. informix) than root and permission 660. The RAW devices are not stable, they are loosing the filerights somtimes. Not only when rebooting! Any idea how to get the file rights stable, please let me know.

Thanks,
Sushant

MensaWater · 10-12-2012, 12:52 PM

I've not done it in Suse for Informix but have in RHEL for Oracle RAC. In the latter one modifies udev raw rules so I did a web search for suse udev raw to see if it had any hits and found one that talks about it for Suse 12 and Informix:

http://informix-zone.com/raw-revices...udev-mechanism

That says:

Quote:

Every time Suse comes with a new version of its operating system we must carefully have a look on how they handle raw devices resp. logical volumes. This week i upgraded from Suse 11.4 to Suse 12.1, IDS remains unchanged on version 11.70. There is no substantial change in handling raw-devices by Suse 12.1, but it is very important to use the correct udev-file. otherwise you can get a surprise - may be that mouse and keyboard does not work....

So what do we need in order to install correct working raw-devices?

First, go to directory /lib/udev/rules.d. Then edit the file 50-udev-default.rules and insert the following row:

KERNEL=="dm-[0-9]*", GROUP="informix", OWNER="informix", MODE="0660"

Save the file and change the owner and group of the logical volumes:

chown informix:informix /dev/dm*

After this owner and group of the raw-devices will NOT change, even if you reboot your system.That's all.

P.S. Please do not copy the old 50-udev-default.rules- File from your 11.4-System (or older) because its not compatible with the new version.

jefro · 10-12-2012, 07:37 PM

I used to see raw devices a lot way way back when. At some point the doc's finally started saying use at your own risk.

MensaWater · 10-16-2012, 08:15 AM

Yep - Back as early as RHEL4 I saw notes saying that raw in Linux was going away but these many years later it still seems to be there and various DBMS products rely upon it.