In my post called Building a Stretch Real Application Clusters Configuration? Get The CRS Voting Disk Setup Right!, I linked to a paper Oracle maintains that explains how to use an NFS export from a small Unix/Linux server as storage for a third voting disk in a stretch RAC cluster. I pointed out that the paper instructs on how to use the noac mount option for Linux RAC clusters in spite of the many resources that suggest actimeo=0 will do. The authors of the document are standing fast that if you are building a Linux-based RAC stretch cluster and are using an NFS mount as a third voting device you do indeed need to mount that particular NFS filesystem with noac. That nugget of truth contradicts so many different documents that I don’t care to list. Instead, I’ll list a resource from Metalink that helps clarify the issue. In fact, I would say that no matter what the sundry Installation Guides or Release Notes say, refer to Metalink 359515.1 when the topic of Oracle Database 10g on NFS filesystems comes up.
Datafiles or CRS Files? The Mount Options Differ.
Metalink 359515.1 is a really helpful note. It spells out the RAC-related mount options for 10gR2 on Solaris, AIX, HP-UX and Linux. Most importantly, it spells out the options for the datafiles and the CRS files in two separate columns. Lo and behold, Metalink 359515.1 clearly spells out that noac is needed for CRS files, but not for datafiles.
In the comment section of Building a Stretch Real Application Clusters Configuration? Get The CRS Voting Disk Setup Right!, a reader points out that the Third Party Vote on NFS paper has a dead end URL (http://www.oracle.com/technology/deploy/availability/htdocs/vendors_nfs.html) in the section that aimed to point out the fact that you cannot just use some Unix/Linux server NFS exports for any other purpose than this unique third voting disk setup in a stretch cluster scenario. He is right, that URL is a dead end, but I’d rather point folks to Linux RTCM (RAC Technology Certification Matrix) or the Unix RTCM, both of which clearly spell out a list of supported NFS File servers. Missing from the list is, of course, some plain old Linux or Unix server dishing out NFS exports-because the only supported application of simple, Unix/Linux NFS exports is the third voting disk scenario in a stretch cluster.
The reader also added this comment:
Many people say Oracle doesn’t support NFS, we need to verify. Searching oracle.com, “We did not find any search results for: vendors_nfs.html” and the references from google all seem to point at that one mysteriously missing doc.
Gee whiz. Where to start? Yes, for the eleventeenth time, NFS filesystems are supported for Oracle Database (including RAC). Let’s not get so easily confused; NFS is a protocol and the storage is NAS. Let’s all enter the following formula in our decoder rings before reading Oracle documents:
(Some Stupid Little Linux/Unix Server Exporting Filesystems via NFS) != NAS
The only supported application of non-NAS NFS is described in the following paper: Using NFS for a Third CRS Voting Device
Now, for some light reading about Oracle on NFS with 11g, I submit:
Oracle Database 11g on NFS filesystems:
Using Network Attached Storage or NFS File Systems Installation Guide for Microsoft Windows
Using Network Attached Storage or NFS File Systems Installation Guide for HP-UX
Using Network Attached Storage or NFS File Systems Installation Guide for AIX 5L Based Systems (64-Bit)
Using Network Attached Storage or NFS File Systems Installation Guide for Solaris Operating System
Using Network Attached Storage or NFS File Systems Installation Guide for Linux
And, of course: Configuring Direct NFS Storage for Datafiles
But, let’s not forget:
- Manly Men Only Deploy Oracle with Fibre Channel Storage – Part I. Oracle Over NFS is Weird.
- Manly Men Only Deploy Oracle with Fibre Channel – Part II. What’s So Simple and Inexpensive About NFS for Oracle?
- Manly Men Only Deploy Oracle with Fibre Channel – Part III. Did I Hear EMC Say NAS?
- Manly Men Only Deploy Oracle with Fibre Channel – Part IV. SANs are Simple, RAC is Difficult!
- Manly Men Only Deploy Oracle with Fibre Channel – Part V. What About Oracle9i on RHAS 2.1? Yippie!
- Manly Men Only Deploy Oracle with Fibre Channel – Part VI. Introducing Oracle11g Direct NFS!
- Manly Men Only Deploy Oracle with Fibre Channel – Part VII. A Very Helpful Step-by-step Install Guide for RAC on NFS.
- Manly Men Only Deploy Oracle With Fibre Channel – Part VIII. After All, Oracle Doesn’t Support Asynchronous I/O On NFS!
Hi Kevin,
Oracle has done a great job in publicizing NFS support, however Metalink 359515.1 leaves much to be desired when it comes to Solaris.
It would appear that Oracle has tested only Linux extensively and not Solaris .
For e.g. Mount options for Data Files on Solaris requires both noac and forcedirectio – It does not make much sense to have both forcedirectio and noac enabled. noac is outdated and the best option would be forcedirectio and actimeo=0.
Again, take the options for binaries – On any sensible RAC installation, the binaries are individual copies on the nodes – why would I want to enable noac for binaries in such a case? noac disables data and attribute caching – it makes simple activities such as installation, patching etc extremely slow.
Thanks
Krishna Manoharan