Re: NFS vs I-NET: **REVISED**

Bass Chorng (bass@octel.com) wrote: : : D. Approach #3 requires that the Informix DBMS binaries are also NFS mounted. : : E. Somebody said that option #3 can not work. Actually this is the way the : : system works right now. This approach is not supported by Informix, but : : works if I-NET is running on the database server. : : Informix's argument for not using this approach is that NFS may mess up : : file locking. I haven't yet been able to identify such problems. : : : These are my comments: : : 1. It works, but I dbout if I-net has anything to do with it. : I have my RDBMS binaries exported from a NFS server : for years, never had any problems. : : 2. I don't understand why it won't work, in fact. How does : Informix know it's not local ? Shouldn't NFS be totally : transparent to applications ? : : The concern I heard on informix's not supporting : NFS is legal matter though. There definitely is a locking deficiency in NFS that does make NFS-mounted files behave differently than local mounted files. Even with the Sun NFS locking daemons, NFS locks are not as robust as local file system locks. Now, if you are NFS mounting Informix binaries, this is not an issue. If you are running Informix SE with the data files mounted via NFS, it definitely is an issue. I am not saying it will not work, but that locking is not 100% effective. It is not a deficiency in NFS coding or the lock daemons, but rather a problem with the NFS transaction model. This issue came up in the BSDI mailing list. The issue was whether NFS lock daemons should be implemented considering the fact that NFS locking was not 100% reliable. The general consensus was that no files should be NFS mounted that may need to be locked, like mail spool files. I would suppose that SE data files are much more valuable than mail files. -- Bruce Momjian | 830 Blythe Avenue root@candle.pha.pa.us | Drexel Hill, Pennsylvania 19026 + If your life is a hard drive, | (610) 353-9879(w) + Christ can be your backup. | (610) 853-3000(h)