Veritas™ File System Programmer's Reference Guide - Solaris

fcl_keeptime

Specifies the duration in seconds that FCL records stay in the FCL file before they can be purged. The first records to be purged are the oldest ones, which are located at the beginning of the file. Additionally, records at the beginning of the file can be purged if the allocation to the FCL file exceeds fcl_maxalloc bytes. The default value is "0". Note that fcl_keeptime takes precedence over fcl_maxalloc. No hole is punched if the FCL file exceeds fcl_maxalloc bytes and the life of the oldest record has not reached fcl_keeptime seconds.

Tuning recommendation: The fcl_keeptime tunable parameter needs to be tuned only when the administrator wants to ensure that records are kept in the FCL for fcl_keeptime length of time. The fcl_keeptime parameter should be set to any value greater than the time between FCL scans. For example, if the FCL is scanned every 24 hours, fcl_keeptime could be set to 25 hours. This prevents FCL records from being purged before they are read and processed.

fcl_maxalloc

Specifies the maximum amount of space in bytes to be allocated to the FCL file. When the space allocated exceeds fcl_maxalloc, a hole is punched at the beginning of the file. As a result, records are purged and the first valid offset is updated in the FCL superblock. The minimum value of fcl_maxalloc is 4MB. The default value is fs_size/33.

fcl_winterval

Specifies the time in seconds that must elapse before the FCL records multiple overwrite, extending write, or truncation records for the same inode. This helps to reduce the number of repetitive records in the FCL. The fcl_winterval time-out is per inode. If an inode happens to go out of cache and returns, its write interval is reset. As a result, there could be more than one write record for that file in the same write interval. The default value is 3600 seconds.

Tuning recommendation: The fcl_winterval tunable parameter should be set to a value that is less than the time between FCL scans. For example, if the FCL is scanned every 24 hours, fcl_winterval should be set to less than 24 hours. This ensures that there is at least one record in the FCL for each file being overwritten, extended, or truncated between scans.

fcl_ointerval

Specifies the time interval in seconds within which subsequent opens of a file do not produce an additional FCL record. This helps to reduce the number of repetitive file-open records logged in the FCL, especially in the case of frequent accesses through NFS. If the tracking of access information is also enabled, a subsequent file open event within fcl_ointerval might produce a record, if the latter open is by a different user. Similar to fcl_ointerval, if an inode goes out of cache and returns, or if there is an FCL sync, there might be more than one file open record within the same open interval. The default value is 600 seconds.

Tuning recommendations: If the application using file-open records only needs to know if a file has been accessed by any user from the last time it scanned the FCL, fcl_ointerval can be set to a time period in the range of the time between the scans. If the application is interested in tracking every access, the tunable can be set to zero.

In the case where the file system is extensively accessed over NFS, depending on the platform and the NFS implementation, there might be a large number of file open records logged. In such cases, it is recommended to set the tunable to a higher value to avoid flooding the FCL with repetitive records.