Firstly, many thanks to the HUGE number of people who replied to my question about NFS mounts of Oracle database files. The response was amazing and the information was really useful. I received a great mix of "fors" and "againsts" and it was a proper maelstrom of thought digesting each mail I can tell you! One email would come in saying it was fine, another not, then another not, then another fine and so on! In short, there are several key points that were raised by those contributing, and I won't paste them all together as the email would be MASSIVE! But first, the thanks list... Martin Hepworth Tim Chapman Kevin Buterbaugh Marc Alvidrez Brian McGraw Gary Mulder Justin Stringfellow Michael Sullivan Dylan Northrup John Leadenham Jeff Kennedy Righty right... onto the good stuff... much plagiarising going on here! But all done in the "best possible taste..." Point 1: The information that I had from Oracle referred to older versions of NFS which relied upon UDP. NFS3 now uses TCP and is since much more reliable. However, NFS is much slower than SCSI and so for a busy database, a Gb ethernet might be in order... Point 2: Oracle assumes that data is safe when it sends a write to disk but NFS actually caches data first. If you lost the NFS server, you lose that data. This was a major point for many people - if the Oracle instances are on another server, then your database may get corrupted by some such event happening and refuse to start back up once the NFS server is back up... Point 3: Oracle (allegedly) support NFS mounts but only when done through "filers". These apparently rename the datafiles so that the database doesn't come up without the DBA if it can't assure the state of the files. A pretty good solution for the problem outlined in Point 2!!! Brian kindly provided this URL for approved vendors... http://www.oracle.com/ip/deploy/database/storage/vendors_nfs.html Point 4: The speed of your network connection will effect the stability of your setup. The speed with which Oracle can write to the storage is central to how efficient the transfers will be. The benefits of NFS is that it's a cheaper (possibly) option that an attached array but, a lot slower. Gary provided these stats: "NFS performance is extremely poor as compared to SCSI. Gigabit ethernet might get you 50MB/sec due to all of the TCP/IP and NFS overhead. Properly configured RAID should provide you 80+MB/sec." To summarise: it can be done but is not advisable unless using a Netapp filer. The risk of losing the NFS server needs to be considered high no matter what server you're using. Oracles data was out of date (the stuff I had) regarding NFS which is worth noting, and they do claim to support this config when used with filers. In theory, you can do this without filers, but in practice, it's not something that you would want to do without them! As a side note, the customer rejected the solution proposed but not on the grounds that the NFS solution may be risky, but that they would RATHER stay with Data General servers... Who says life is dull? Thanks to all! Callum A. Hughes Unix Systems Engineer Securicor Information Systems e: callum.hughes@sis.securicor.co.uk ********************************************************************** The information contained in this e-mail message is intended only for the individuals named above. If you are not the intended recipient, you should be aware that any dissemination, distribution, forwarding or other duplication of this communication is strictly prohibited. The views expressed in this e-mail are those of the individual author and not necessarily those of Securicor Information Systems Limited. Prior to taking any action based upon this e-mail message you should seek appropriate confirmation of its authenticity. If you have received this e-mail in error, please immediately notify the sender by using the e-mail reply facility. ********************************************************************** _____________________________________________________________________ This message has been checked for all known viruses on behalf of Securicor Information Systems by the MessageLabs. For further information visit http://www.messagelabs.com or Email: mailsweeper.info_at_sis.securicor.co.uk _______________________________________________ sunmanagers mailing list sunmanagers@sunmanagers.org http://www.sunmanagers.org/mailman/listinfo/sunmanagersReceived on Thu Apr 4 04:01:27 2002
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