Red Hat GLOBAL FILE SYSTEM 5.2 Installationsanleitung PDF herunterladen (Seite 42)

Directory

Specifies the directory where the inherit_directio flag is set.

Example

In this example, the command sets the inherit_directio flag on the directory named

/mnt/gfs/data.

gfs_tool setflag inherit_directio /mnt/gfs/data

This command displays the flags that have been set for the /mnt/gfs/data directory. The full

output has been truncated.

[root@tng3-1 gfs]# gfs_tool stat /mnt/gfs/data

...

Flags:

inherit_directio

9. Data Journaling

Ordinarily, GFS writes only metadata to its journal. File contents are subsequently written to disk

by the kernel's periodic sync that flushes file system buffers. An fsync() call on a file causes

the file's data to be written to disk immediately. The call returns when the disk reports that all

data is safely written.

Data journaling can result in a reduced fsync() time, especially for small files, because the file

data is written to the journal in addition to the metadata. An fsync() returns as soon as the

data is written to the journal, which can be substantially faster than the time it takes to write the

file data to the main file system.

Applications that rely on fsync() to sync file data may see improved performance by using data

journaling. Data journaling can be enabled automatically for any GFS files created in a flagged

directory (and all its subdirectories). Existing files with zero length can also have data journaling

turned on or off.

Using the gfs_tool command, data journaling is enabled on a directory (and all its

subdirectories) or on a zero-length file by setting the inherit_jdata or jdata attribute flags to

the directory or file, respectively. The directory and file attribute flags can also be cleared.

Usage

Setting and Clearing the inherit_jdata Flag

Chapter 3. Managing GFS

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 57 58

Keine Kommentare

Red Hat GLOBAL FILE SYSTEM 5.2 Installationsanleitung Seite 42