Open System Services Management and Operations Guide (G06.29+, H06.07+)

Managing Filesets
Open System Services Management and Operations Guide—527191-005
5-18
Changing OSS File Caching for the Disks of a
Fileset
Changing the OSS File System Mount Point
Changing the mount point can affect the behavior of programs that use OSS files,
particularly programs that use the symbolic-link feature. You should notify users well in
advance of changing an existing mount point.
Changing OSS File Caching for the Disks of a Fileset
You should decide whether to use OSS file caching when you first configure a fileset,
because changing the use of OSS file caching requires you to stop the fileset. For
more information about OSS file caching, see OSS File-System Components on
page 1-10 and OSS File Caching Overview on page 5-20.
If you want to enable OSS file caching initially for all disk volumes that contain OSS
files, you need do nothing. OSS file caching is enabled by default when disk volumes
are configured.
LOG An OSS name server does not write PXLOG records; it checkpoints these
records to its backup process. The backup process of an OSS name server
keeps these records in its memory and uses them to recover partially completed
operations in the event of a failure of an OSS name server primary process. If
total failure of an OSS name server occurs, FSCK is automatically run against
the fileset during the fileset remounting operation.
This option provides better performance for fileset catalog updatesat the
expense of slower recovery in the event of complete OSS name server failure.
You can control the relative likelihood of needing fileset repair, and therefore the
relative speed of recovery, by adjusting the MAXDIRTYINODETIME attribute for
the fileset.
CREATE The OSS name server does not write PXLOG records but rather checkpoints
these records to its backup process. The backup process keeps these records
in its memory and uses them to recover partially completed operations in the
event of a failure of the OSS name server primary process. If total failure of the
OSS name server occurs, FSCK is automatically run against the fileset during
the fileset remounting operation.
The disk process does not write new file labels immediately but rather defers
these label writes until it has nothing else to do.
This option provides the best performance for fileset catalog updatesbut limits
the fileset to one disk volume and has the potential for lost files in the event of a
double-disk process failure. See Creating a Unique Fileset
on page 5-1 for
additional considerations when you use BUFFERED CREATE.
Note. HP recommends that you not modify OSS file caching at the disk level. The FTIOMODE
and NORMALIOMODE fileset attributes now provide better control over fault-tolerance and
performance for file input or output. See Table 5-1
on page 5-16 to map OSSCACHING ON
and OFF settings to the use of the new attributes.
Value When to use it (continued)