storage options


  • shared Storage and voting disk Options :
  • Someone can used VMware because it allowed them to make shared storage.shared storage is mandatory for having a clustered filesystem.
  • This means you have to have shared scsi or firewire (the most lowcost option), have a network with a node being an iscsi server (and having the nodes of the cluster access it using the iscsi initiator), or having normal shared storage. (or oracle’s virtualisation product of course)
  • When a filesystem is clustered but native, there has to be lock management.
  • LVM is not mandatory for GFS (but I am not a GFS expert by any means)
  • starting from 10.2.0.2, cluster&voting disks may be ordinary blockdevices, so you do not have to have a clustered filesystem. use UDEV to fix blockdevice naming (otherwise adding/removing scsi devices can result in different naming, even for still present disks)

So you can have

  • To install oracle clusterware (grid infratstructure) you need shared storage for ocr and voting disks. The shared storage can be provided by using one of the following or their combination1.NFS (supported NAS) mount points2. ASM (can use both iscsi/san luns)

    3. supported cluster file system (such as ocfs2 or gfs)

    raw or block devices are not supported any more for oracle 11g r2 grid infrastructure and rac for new installations but can be used if you are upgrading from a previous release.

NOTE

  • For GFS you must have three nodes.
  • 1)rac-1 (for rac instances and share disks.)
  • 2)rac-2 (for rac instances and shaared disks.)
  • 3)External Lock Manager

Think Twice Before Using Cluster File System :

  • Using a cluster filesystem for files which need administration (for example: the oracle database) makes much sense. Using raw devices effectively makes you ‘blind’.
  • For the CSS daemons however, the two files are static in size, thus don’t need any administration. Setting up a cluster filesystem just for voting & cluster registry would seem a very high overhead to me. This is why those files are put onto raw devices or straight onto blockdevices in all tutorials you find. you’ll add administration and installation of GFS, for two (or more, if they have been setup redundant) files which don’t need administration.
  • You can use OCR + VOTE on OCFS – If node02 (private NIC) can not communicate with node01, that can make node02 kernel panic… so have to set kernel.panic=60 at sysctl.That’s a bad thing, I don’t like it. On 10g -> 11gR1 … we’ll use raw device for OCR and VOTE DISK. 11gR2 go to ASM.
  • If you have plan to use ASM, I think raw device is a good way for OCR + VOTE DISK + ASM SPFILE.
  • GFS puts an extra layer.Remember that voting disks are very sensitive to freeze and delays. If this situation happens Your node will be evicted.

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