PRIMECLUSTER Global File Services Configuration and Administration Guide 4.2 (Solaris(TM) Operating Environment)

2.4 High-speed Recovery of the File System

The GFS Local File System contains an update log function for recording updates that were made to the structure of the file system. This function enables the file system to recover from system failure within a few seconds to a minute or so.

When the GFS Local File System recovers from a system failure, the fsck_sfxfs(1M) command of the file system scans the update log and invalidates or completes file system operations that were being performed at the time the system failure occurred. The file system can be mounted and used soon afterwards, without the need for a full check of the file system structure.

The fsck_sfxfs(1M) full check mode is supported as well. A full check by fsck_sfxfs(1M) may be required when a disk has to recover from a hardware failure.

The size of the update log area can be specified by an option of sfxnewfs(1M). The default value for this operation is 1% of the size of the file system. However, if 1% of the file system size is less than 5 MB, the default value is set to 5 MB. If it exceeds 50 MB, the default is set to 50 MB.

A larger update log area can improve file system performance, but may increase the time that is required for file system recovery. It is recommended to specify an update log area size of no more than 50 MB.

The update log area can be allocated in a separate partition to avoid that the I/O operations for log updates degrade file system performance. See the sfxnewfs(1M) option for this function.