3.5.1 Matrix Server Administration Guide

Chapter 7: Configure PSFS Filesystems 122

Because atime updates can have a performance impact, and to maintain

the same behavior as in previous versions of the PSFS filesystem, the

atime update feature is disabled by default. If needed, the feature can be

enabled on specific nodes. A filesystem mounted on those nodes will

perform atime updates unless the feature is disabled specifically for that

filesystem at mount time.

NOTE: Access times are never updated on read-only filesystems.

Enable atime Updates for a Node

To enable the atime update feature on a node, you will need to edit the

/etc/opt/polyserve/mxinit.conf configuration file on that node. Add the

following parameter to the file:

psfs_atime_enabled = 1

By default, the atime for a file is updated whenever the file is accessed;

however, you may want an update to occur only after a specific number

of seconds have passed since the file was last updated. This can minimize

the performance impact of atime updates for files that are accessed

frequently (at the cost of sometimes seeing stale access times).

To specify an update period, add the following parameter to the

mxinit.conf file:

psfs_atime_resolution_seconds = <seconds>

The default is 0, which means that atimes are updated whenever files are

accessed. If <seconds> is set to a different value N, then a file’s atime will

be updated when it is accessed only if it has been at least N seconds since

it was last updated.

Disable atime Updates for a Filesystem

By default, atime updating is done on all filesystems (other than read-

only filesystems) that are mounted on a node on which atime updates

have been enabled. However, if you do not want atime updates to occur

for a specific filesystem, you can disable the feature for that filesystem. To

disable atime updates, mount the filesystem with the -o noatime option.