US Robotics 7931 Uživatelská příručka stáhnout pdf (Strana 140)

116 Sun StorageTek SAM Archive Configuration and Administration Guide • Version 4, Update 6, 04/07

2. Scans the file system and collects information about each file.

3. Begins releasing files in priority order.

A file system can contain thousands of files. Keeping track of the release priority for

every file can be wasteful because releasing only several large files might return the

file system to its low-water mark. However, the releaser must examine the priority of

each file or risk missing the best candidates for release. The releaser does this by

identifying the first 10,000 candidates. It then discards subsequent candidates if they

do not have a priority greater than the lowest-priority candidate among the first

10,000.

After the releaser has determined the priority of the first 10,000 candidates, it selects

the files with the highest priority for release. After releasing each file, the releaser

checks whether the file system cache utilization is below the low-water mark. If so, it

stops releasing files. If not, it continues releasing the files in priority order.

If the releaser has released all 10,000 candidates and the file system is still above the

low-water mark, it starts over and identifies 10,000 new candidates.

The releaser exits if it cannot find any viable candidates. This can occur, for example,

if files do not yet have archive copies. If this happens, the Sun StorageTek SAM

software starts the releaser again after one minute has elapsed.

The high and low-water marks are set with the high=percent and low=percent file

system mount options. For more information about these mount options, see the

mount_samfs(1M) man page.

Releaser Concepts

This section describes concepts that are basic to the releaser process:

■ Age – The amount of elapsed time from a given event until now. A file’s inode

keeps track of the following times for use by the releaser:

■ Residence-change time

■ Data-modified time

■ Data-accessed time

You can view these times by using the sls(1) command with the -D option. Each

time has a corresponding age. For example, if it is 10:15 a.m., a file with a modify

time of 10:10 a.m. has a data-modified age of five minutes. For more information

about the sls(1) command, see the sls(1) man page.

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