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Partitions in RAC [message #74976] Wed, 16 February 2005 03:25 Go to next message
Messages: 1
Registered: February 2005
Junior Member
Hi all, must I create a partition of ocfs type in each node of my cluster or it is created only in one node and then 'exported' to be mounted by the others, for example, via samba or nfs? If it is to be shared, it´s done like any other shared device in samba? Some change in ocfs or system file to show this share to the other nodes? Please clarify this to me, the documentation found is not clear in this issue.
Re: Partitions in RAC [message #111296 is a reply to message #74976] Tue, 15 March 2005 08:04 Go to previous message
Michael Hartley
Messages: 110
Registered: December 2004
Location: West Yorkshire, United Ki...
Senior Member


If you're using OCFS you are probably using Linux rather than Windows, so I'll step through using Linux terminology.

1. partition the disks/LUN's using fdisk into disk partitions that are large. I recommend large because you will not have access to a partition manager and resizing partitions is virtually impossible, especially in a production systems.
2. If the partitions have not been detected by the operating system perform a system reboot.
3. For each partition you want OCFS on.
mkfs.ocfs -g dba -u oracle -b 128 -L $mountpoint -m $mountpoint -p 0755 $device

-g = groupid
-u = userid
-b = blocksize
-L = Label
-m = mount point
-p = file permision on mount point

where $mountpoint is /u01 /u02 and so on.
where $device is the partition /dev/sdb1 /dev/sc1 and so on.
4. Mount the file system on all nodes participating in the cluster.
mount -t ocfs $device $mountpoint
5. Make the /etc/fstab entries on both nodes
echo -e "$device\t$mountpoint\tocfs\t_netdev,noatime\t0\t0" >> /etc/fstab


But be carefull with file system fragmentation, as OCFS is an early software project and is still maturing, fragmentation and performance can be an issue.

In general, only create large oracle database files, ensure archive logs only get written to their own file system, also ensure each node in the cluster has it's own OCFS for archive logs ( this reduces global file system locking ). Don't ever put the Oracle Home on OCFS. Keep to less than 20 OCFS mount points and 50 as an absolute maximum.

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