[SunHELP] solaris 8 NFS - hard/soft mount definintions

[Adrian Florea]

Hi,


Thank you very much for your advices.
My real problem is that I must take some actions when NFS server is down
(let say that a network problem appears, such as a unplugged cable), and
for taking those actions I need a working machine. Now, in case of my NFS
clients (fs are mounted for read and write purposes, so 'soft' is not a
good option) I need to kill some processes on them when NFS server is
down, but when server is down my clients are blocked and I cannot even
execute 'ps' to see processes.


Adrian FLOREA.




On Fri, 28 Jun 2002, Ahmed Afrose wrote:

> HARD MOUNTS are permanent mounts designed to look just like any normal, local
> file system. If a partition
> that is hard mounted becomes unavailable, client programs will keep trying to
> access it forever. This will
> cause local processes to lock when a hard mounted disk goes away. Hard mounts
> are the default type of mount.
>
> SOFT MOUNTS will fail after a few retries if a remote partition becomes
> unavailable. This is a problem if
> you are writing to the partition, because you can never be sure that a write
> will actually get processed
> on the other hand, your local processes will not lock up if that partition
> does go away. In general, soft
> mounts should only be used if you are solely reading from a disk and even
> then it should be understood that
> the mount is an unreliable one. If you soft mount a partition that will be
> written to, you are nearly
> guaranteeing that you will have problems.
>
>
> Ahmed Afrose wrote:
>
> > This might help, in NFS there are hard mounts and soft mounts do a man
> > mount and check the definitions, by default i beleive its a hard mount
> > wchich makes the client wait/hang till the NFS is responding/ok so try
> > soft mounting but keep in mind "soft" mounts may cause inconsistancies.
> > //
> >
> > NFS SERVER NOT RESPONDING means that many things could be at fault:
> > 1.  The server is down or unable to respond (e.g. too busy)
> > 2.  The network is not reliable
> > 3.  Software or firmware problems on any component in the network,
> > possibly
> >     including the NFS client and/or NFS server.
> >
> > For case 1, lighten the load of the server, or migrate files to a less
> > busy
> > server.
> >
> > For case 2 and 3, we recommend the following workaround of
> > changing mount options, as in the following  examples:
> >
> > /usr/etc/mount -orsize=1024,wsize=1024,timeo=15 server:/disk /mnt
> > (SunOS)
> >
> > /usr/sbin/mount -F nfs  -o rsize=1024,wsize=1024,timeo=15 server:/disk
> > /mnt
> > (Solaris)
> >
> > The 1024 read and write packet size allows NFS requests/responses to
> > squeeze
> > inside a single network (e.g. ethernet) packet instead of the default 8k
> > size.
> > The helps eliminate fragmentation across a bridge or router, as well as
> > UDP packet reassembly, although the actual NFS performance is somewhat
> > slower.
> >
> > Increasing the initial request timeout from 7 to 15 (units are tenths of
> >
> > seconds) often helps in congested networks.
> >
> > Please note that we also recommended installation of any NFS and Kernel
> > jumbo patches.
> >
> > Adrian Florea wrote:
> >
> > > Hello,
> > >
> > > Please, knows somebody  how to prevent  NFS client in Solaris 8 from
> > > hanging  when NFS server down ?
> > >
> > > When NFS server is down the clients are allmost dead.
> > >
> > > Thank you very much,
> > > best regards,
> > >
> > > Adrian Florea.
> > > _______________________________________________
> > > SunHELP maillist  -  SunHELP at sunhelp.org
> > > http://www.sunhelp.org/mailman/listinfo/sunhelp
> >
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