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

12.3.2 High-speed file system recovery

In case of a node failure, fsck(1M) must be executed for ordinary file systems to recover consistency. In most file systems, it is necessary to inspect all of the meta-data for the systems in order to recover consistency. If a node failure occurs, a large amount of time may be required until the file systems can actually be used.

The GFS Shared File System records operations that have changed the file system structure in an area called update log. These operations include file creation and deletion. Using the log in the update log area allows the file system to recover from a system failure in less than a minute.

When recovering from a system failure, the GFS Shared File System retrieves the update log during the recovery process. The file system then decides whether to invalidate or complete the file system operation that was in process, and reflects the result. The file system structure can then be mounted and used without fully checking it.

As mentioned in the previous section, the GFS Shared File System operating on multiple nodes does not require execution of fsck_sfcfs(1M) because consistency recovery processing is performed in case of a node failure.

The fsck_sfcfs(1M) full check mode is also provided. To recover the file system from a hardware failure on the disk, execution of full check fsck_sfcfs(1M) may be required.

A function for generating an update log area in another partition is provided in order not to lower file system performance during the update log I/O process, see Appendix "F.2.14 sfcnewfs(1M)."