When Tivoli® Storage Manager connects
a backup-archive client to an NFS file system, you can use either
a hard mount or a soft mount.
Tivoli Storage Manager uses
the nfstimeout option value to determine how
long to wait for an NFS system call to respond before timing out;
this setting applies to hard and soft mounts. The default is 0 seconds.
This means that Tivoli Storage Manager uses
the default behavior of NFS system calls.
Be aware of the consequences of hard and soft mounts if the mount
becomes stale (for example, if the server for the file system is not
available).
- Hard mount
- If the NFS file system is hard mounted, the NFS daemons try repeatedly
to contact the server. The NFS daemon retries will not time out, they
affect system performance, and you cannot interrupt them, but control
returns to Tivoli Storage Manager when
the nfstimeout value is reached.
- Soft mount
- If the NFS file system is soft mounted, NFS tries repeatedly to
contact the server until either:
- A connection is established
- The NFS retry threshold is met
- The nfstimeout value is reached
When one of these events occurs, control returns to the calling
program.
Note: On UNIX and Linux systems, the
nfstimeout option
can fail if the NFS mount is hard. If a hang occurs, deactivate the
nfstimeout option
and mount the NFS file system soft mounted, as follows:
mount -o soft,timeo=5,retry=5 machine:/filesystem /mountpoint
The
parameters are defined as follows:
- soft
- Generates a soft mount of the NFS file system. If an error occurs,
the stat() function returns with an error. If the
option hard is used, stat() does not return until
the file system is available.
- timeo=n
- Sets the timeout period for a soft mount error to n tenths
of a second.
- retry=n
- Sets the number of times to try the mount, where n is
an integer; the default is 10000.
