|
|
United States-English | |
|
|
 |
|
HP 9000 Systems: HP JFS 3.3 and HP OnLineJFS 3.3 VERITAS File System 3.3 System Administrator's Guide > Chapter 1 The VxFS File System
Extended mount Options |
|
|
The VxFS file system supports extended mount options to specify:
See Chapter 5 “Performance and Tuning ” and mount_vxfs(1M) for details on the VxFS mount options.
The HFS file system is "buffered" in the sense that resources are allocated to files and data is written asynchronously to files. In general, the buffering schemes provide better performance without compromising data integrity. If a system failure occurs during space allocation for a file, uninitialized data or data from another file may appear in the extended file after reboot. Data written shortly before the system failure may also be lost. In environments where performance is more important than absolute data integrity, the preceding situation is not of great concern. However, VxFS supports environments that emphasize data integrity by providing the mount -o blkclear option that ensures uninitialized data does not appear in a file. VxFS provides the mount -o mincache=closesync option, which is useful in desktop environments with users who are likely to shut off the power on machines without halting them first. In closesync mode, only files that are written during the system crash or shutdown can lose data. Any changes to a file are flushed to disk when the file is closed. The HFS file system is asynchronous in the sense that structural changes to the file system are not immediately written to disk. File systems are designed this way to provide better performance. However, recent changes to the file system may be lost if a system failure occurs. More specifically, attribute changes to files and recently created files may disappear. The default logging mode provided by VxFS (mount -o log) guarantees that all structural changes to the file system are logged to disk before the system call returns to the application. If a system failure occurs, fsck replays any recent changes to preserve all metadata. Recent file data may be lost unless a request was made to sync it to disk. VxFS provides the mount -o delaylog option which increases performance by delaying the logging of some structural changes. However, recent changes may be lost during a system failure. This option provides at least the same level of data accuracy that traditional UNIX file systems provide for system failures, along with fast file system recovery. On most UNIX systems, temporary file system directories (such as /tmp and /usr/tmp) often hold files that do not need to be retained when the system reboots. The underlying file system does not need to maintain a high degree of structural integrity for these temporary directories. HP OnLineJFS provides superior performance for synchronous write applications. The default datainlog option to mount greatly improves the performance of small synchronous writes. The convosync=dsync option to mount improves the performance of applications that require synchronous data writes but not synchronous inode time updates.
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 Printable version |
|
|
|
|
|
|||||||||||||||
|
|||||||||||||||
