Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!thunder.mcrcim.mcgill.edu!snorkelwacker.mit.edu!usc!cs.utexas.edu!uunet!uaisun4!mrl From: mrl@uai.com (Mark R. Ludwig) Newsgroups: comp.unix.aix Subject: Re: Control NFS exported filesystems Message-ID: <1991Jun19.154830.17276@uai.com> Date: 19 Jun 91 15:48:30 GMT References: <91169.000329CALT@SLACVM.SLAC.STANFORD.EDU> <8567@awdprime.UUCP> Sender: mrl@uai.com (Mark R. Ludwig) Reply-To: mrl@uai.com (Mark R. Ludwig) Organization: Universal Analytics, Inc., Playa del Rey (LA), CA Lines: 54 In-Reply-To: marc@ekhomeni.austin.ibm.com (Marc Wiz) In article <8567@awdprime.UUCP>, marc@ekhomeni (Marc Wiz) writes: >In article <91169.000329CALT@SLACVM.SLAC.STANFORD.EDU>, >CALT@SLACVM.SLAC.STANFORD.EDU writes: >> By exprience, I learned that mounting NFS filesystems by the >> hard/foreground options may cause the machines hanging, while >> by the soft/backgroud options seems to work OK. >> > >To put it mildly this is not a good thing to do. Remember if you mount the >filesystem soft the client process will get an error after three >retries. If your >application can handle this fine but I have to wonder how many applications >can not. If you care about your data I recommend hard mounts. At least when >the server/network comes back up the data will be written/read to/from >the server. I agree fully. At least one of the Sun administration manuals states it bluntly: if you are mounting the NFS read/write, you should mount it hard. To do otherwise is to risk corrupted files. However, I believe if you have *very* intelligent applications manipulating the files, you may disregard this warning, but I dare say the average Unix utility is not in this category. Furthermore, why would you want this? Since your application probably really wants to write the file it was trying to write when the server went silent, then your application has to keep trying until the server responds. With ``hard'' the system does it for you. The second part which I want to address is the foreground/background part. We use the ``bg'' option routinely, because the NFS partitions are not required for the system to operate, and this allows the system to finish multi-user startup without mounting all the NFS partitions. The NFS partitions are only required for certain applications to run. If the partition is required for the system, you probably must use foreground. >> Here comes a problem: If some machine DOES mount my exported filesystems >> by the hard/foreground optins, it may cause my machines hanging. Is there >> any way to configure my exporting filesystems as follows: >> Only the machines which use the soft/backgronud options will be allowed >> to use my exported filesystems. Come again? You're saying that the *server* is hanging because the *client* mounts the NFS hard? I've never seen that happen. >What are you trying to accomplish? Right. This is the first question we have to ask. It helps to get answers when you explain what you really want to do, and the circumstances which caused you to be wedged into the corner. Maybe then we can get you centered in the room.$$ -- INET: mrl@uai.com UUCP: uunet!uaisun4!mrl PSTN: +1 213 822 4422 USPS: 7740 West Manchester Boulevard, Suite 208, Playa del Rey, CA 90293 WANT: Succinct, insightful statement to occupy this space. Inquire within.