Comments on: Running RAC and ASM on Linux (Finally!)

By: sdquirra

sdquirra — Wed, 13 Aug 2008 09:29:40 +0000

hi,
using /dev/sd* devices for ocr and voting disk, i’m getting a “the location /dev/sdb1, entered for the oracle cluster registry (ocr) is not shared across all the nodes in the cluster….”.
This post also http://forums.oracle.com/forums/thread.jspa?threadID=641837&tstart=0&messageID=2474588 says that, for ocr and voting disk, 10g keep using raw dev or cluster fs.
It is correct?
thnx

By: Grégory

Grégory — Thu, 13 Mar 2008 12:50:49 +0000

the answer with Linux is :
a- prefer using ASMLib. In particular is enables to discover the disks on all nodes without partprobe and it is optimized for ASM.
b- If you cannot, use the block device, i.e /dev/sdb* and NOT raw devices

By: Cristian Cudizio

Cristian Cudizio — Wed, 12 Mar 2008 20:28:20 +0000

sorry, i don’t understand one thing: can i use directly /dev/sdb* for asm disks with 10gR2? it seems to me that also in 11g documentation Oracle says to use ASMLib but i can’t find ASMLib very useful. Morehover i’ve met problem described in Metalink Note 457369.1 that suggest to use asm_diskstring = /dev/oracleasm/disks/* but devices files under /dev/oracleasm/disks/* have same major e minor numbers of original block devices (/dev/sdb*) so i think that is the same think. So my question is: does oracle support the use of asm_diskstring=/dev/sdb* ?

Compliments for the post.

Thanks,
Cristian

By: Oracle Clusterware on RHEL5/OEL5 with udev and multipath : Ardent Performance Computing

Thu, 14 Feb 2008 05:38:58 +0000

[…] no permissions.d directory on RHEL5 and OEL5. Last September, Grégory Guillou from Pythian blogged about installing on Red Hat 5 and referenced a post on his French blog that shows how to setup a RULES file for SCSI block […]

By: Grégory

Grégory — Tue, 25 Sep 2007 03:19:21 +0000

Gawie,

Lets start with the bad news : My original post about raw devices is in French !

What it says is that with RHEL5/OEL5, the /etc/udev/permissions.d directory doesn’t exist anymore and you have to create a file under /etc/udev/rules.d to set the permissions on boot ; you should be able to get the content of the file from the post even if it’s in French !

Regarding Oracle recommendation about “raw vs block” devices you’ll find a couple of informations in different 11g docs :

1- (About 10g first) This section explains that starting with clusterware 10.2 and RHEL4, you can use block (instead of raw) devices to store the OCR and the voting disk.

2- (11g) In this section, the doc says that Oracle recommends using block rather that raw devices on Linux. BTW, this section explains how to configure block devices while storing one file per block device (As you use to do with raw devices).

3- (10g and 11g) This section explains that Oracle recommends using block devices with ASMLib to create ASM disks. This OTN page contains the supported release of ASMLib, including the one for RHEL4 and RHEL5. Well (Shame on me !) this is not what I did ! I’ve changed the asm_diskstring parameter and I’ve bound the ASM DISKS to the block devices. I probably shouldn’t ! I’m pretty sure the problem I’ve encountered with lsdsk will be solved by doing the setup this way : I’ll check soon !

Anyway 1 and 3 show that you don’t need the raw devices anymore (even with 10g and RHEL4). But it doesn’t prevent you to set the permission via the “udev” dynamic device naming.

By: Gawie

Gawie — Mon, 24 Sep 2007 22:07:37 +0000

Hi Gregory,

Could you point me to the previous posts regarding etc/udev/rules.d and the fact that no RAW devices are needed anymore.

Thank you for the information in this post
Gawie