test veritas logo



fcladm - VxFS File Change Log administration utility


fcladm clear eventlist mount_point

fcladm -s savefile dump mount_point

fcladm [-s savefile] off mount_point

fcladm [-o version=ver] on mount_point

fcladm [-cdfghit] print offset mount_point

fcladm -s savefile restore restorefile

fcladm rm mount_point

fcladm set eventlist mount_point

fcladm state mount_point

fcladm sync mount_point




The fcladm command performs online administration functions for the Veritas File System File Change Log (FCL) feature. This includes operations such as activating, deactivating, and removing the FCL; specifying the set of events for tracking; and saving and restoring the FCL file for off-host processing. The fcladm command also enables you to set a synchronization point in the FCL, display the current FCL state, or print the contents of the FCL in ASCII format.

The File Change Log is a quasi-regular file in the file system namespace that resides at mount_point/lost+found/changelog. This file can be opened, read, and closed. You can also seek to offsets within the file. However, to prevent corruption of the FCL, operations such as write, rename, and memory mapping are prohibited. The FCL file contains an FCL superblock that stores the meta-information about the FCL, followed by a number of FCL records. Each FCL record typically contains information such as file or directory changes along with the type of change. In addition, each record by itself, or in conjunction with adjacent records, tracks a file system event.

When a file system is created and mounted, the FCL is not enabled by default. Changes to the files and directories of the file system are not automatically logged in the FCL. You must enable the FCL using the on keyword. A newly created FCL initially contains only the superblock, along with the superblock state. To stop logging file system activity, use the the off keyword to de-activate the FCL. When the FCL is off, the FCL file remains at mount_point/lost+found/changelog. You can only remove or delete the FCL by using the rm keyword.

If needed, applications may offload FCL processing to a different system. However, physical layout restrictions may prevent the direct transfer of an FCL file to an off-host system. In such cases, you must first transfer an image of the FCL using the dump keyword. You can then restore the saved fileimage on an off-host system using the restore keyword.

The FCL was first introduced in VxFS 4.0. Version 3 was the FCL version for VxFS 4.1. Version 4 is the default version for VxFS 5.0. For backwards compatibility, VxFS 5.0 supports both versions 3 and 4.

Cluster File System Issues

No cluster issues; the command operates the same on cluster file systems.


The synchronization point in the FCL can also be set using the VxFS FCL sync API. See the vxfs_fcl_sync(3) manual page.

fcladm operates only on file systems using the Version 6 or later disk layout.

The FCL feature is not available on file systems created with the nolargefiles option.

Only a superuser can run the fcladm command.

The VX_FCL_MTIME_CHG record is updated when the time stamps of the inode are changed by an external event, such as the touch command. During a read or write access of the file, the record is not updated for atime or mtime changes.

Access control lists updates do not produce a mode change record.

In some cases, the state printed by the state keyword might differ from the state displayed in the FCL superblock by the print keyword. For example, if the FCL is turned on when a Storage Checkpoint is created, the fcladm print command shows the FCL superblock state as ON. However, if the Storage Checkpoint is mounted as read-only, the fcladm state command shows the Storage Checkpoint state as OFF. No activities are recorded in the FCL file for a read only file system.

If a future release of VxFS containing an FCL file higher than Version 4 is ever downgraded to VxFS 5.0, most fcladm keywords may not function properly. In such cases, it is recommended to remove the higher version FCL file using fcladm rm and to re-activate it using fcladm on.


clear Disables the recording of events specifed in the eventlist for the File Change Log.
dump Creates a regular file image of the FCL file that can then be sent to an off-host processing system. This file has a different format than the FCL file. You must restore the file with the restore keyword, before it can be processed through the FCI API.
off Deactivates the FCL on a mounted file system and clears the FCL contents. Use the -s option to save a copy of the FCL as needed. See OPTIONS.
on Activates the FCL on a mounted file system. VxFS 5.0 supports either FCL file versions 3 or 4. You can specify the version with the on keyword. If no version is specified, fcladm defaults to Version 4.
print Prints the contents of the the FCL file starting from the specified offset. If the offset is 0, print displays the FCL super block, which occupies the first block of the FCL file. Otherwise, print displays the FCL records starting from the specified offset to end of the FCL file using the standard output.
restore Restores a file from an FCL image created by dump keyword. The restored file created by the restore keyword produces a formatted file that can be sent to the FCL API.
rm Removes the FCL file. You must first deactivate the FCL before removing an FCL file.
set Enables the recording specified by the eventlist for the FCL. More than one option can be set to enable the simultaneous logging of multiple events. See OPTIONS.
state Writes the current state of the FCL to the standard output.
sync Brings the FCL to a stable state by flushing the associated data from an FCL recording interval. For cluster file systems, sync also merges the private views or individual FCL records into a single FCL file. In addition, sync prints a standard output of the last offset into the FCL file before the sync operation takes place.
Certain events such as data writes have an associated time interval that specify when the write event can be logged in the FCL. If a write event falls inside the time interval, it is not logged. See fcl_winterval in the vxtunefs(1M) manual page. sync also resets the FCL write interval for data write records, which forces the next write to each file in the file system to write a record in the FCL file.


  Specifies where the directory of the file system containing the File Change Log is mounted.
ver Specifies the version of the FCL file to be created. This can be either Version 3 or 4. If no version is specified, the default is 4.
offset Specifies an offset (in bytes) in the FCL file. This indicates where to begin printing the FCL file. Use this option in combination with the print keyword to produce an ASCII display of the FCL contents. The offset must always be 32-byte aligned.
savefile Specifies the name of the saved FCL file image. This image can be shipped to a different system and restored for off-host processing.
  Specifies the name of the FCL file to restore that was created earlier by savefile. The restored file is a regular file, unlike the original FCL file.
eventlist Specifies a list of the following events: accessinfo, fileopen, filestats. You may list multiple events, by separating them with a common. Use this option in conjunction with the set or clear keywords to optionally turn on or off the recording of the specified events.
  Enables recording information about the process that accessed the file in each FCL record. This includes the process ID, the real and effective user and group IDs of the process, and the ID of the node from which the file or directory was accessed. The node ID is significant only in cases where the file system is mounted from multiple nodes. The node ID is specified in the LLT configuration.
  Enables file open recordings. Whenever a file is opened, this results in an FCL record that contains the command name of the process that opened the file.
  Enables recording of file I/O statistics to the FCL. The FCL is used as a persistent store for the collected I/O statistics. When logging of this event is enabled, the I/O statistics collected in-core, get written to the FCL periodically. For I/O statistics to be collected in-core, the fiostats_enable tunable for the file system should be set to 1.
The following options are valid only with the print keyword.
-c Prints the change type field.
-d Prints the directory inode number field. The directory inode is only stored in an FCL record when the record is a VX_FCL_LINK, VX_FCL_UNLINK, or VX_FCL_RENAME FCL change type.
-f Prints the file name field. The file name is only stored after an FCL record when the record is a VX_FCL_LINK, VX_FCL_UNLINK, or VX_FCL_RENAME FCL change type.
-g Prints the inode generation count field.
-h Displays the field names before printing the contents of the FCL.
-i Prints the inode number field.
-t Prints the time stamp field.


To turn on the FCL for the file system mounted on /home, type the following:

# fcladm on /home

To turn off the FCL for a file system mounted on /export/data, type the following:

# fcladm off /export/data

The following example removes the FCL file for a file system mounted on /export/reports. The FCL must be OFF before it can be removed.

# fcladm rm /export/reports

To turn on the logging of file openings for the file system mounted on /home once the command is executed, type the following:

# fcladm set fileopen /home

To turn off the logging of file openings for the file system mounted on /home, type the following:

# fcladm clear fileopen /home

To obtain the current FCL state for a file system mounted on /home, type the following:

# fcladm state /home

To disable the logging of file opens, file I/O statistics, and access information for the file system mounted on /home, type the following:

# fcladm clear fileopen,filestats,accessinfo /home

To print all the FCL records present in an FCL file, you can print the contents of the FCL superblock by skipping offset 0, and using the first valid offset (foff) as an argument to the subsequent print.

For example, to print an ASCII display of the on-disk FCL superblock from offset 0 and to obtain information about the FCL for the file system mounted on /export/data, type the following:

# fcladm print 0 /home magic a506fcf5 version 2 time 1087979247 930092 (Wed 23 Jun 2004 04:27:27 PM CST CDT) state ON sync 1 foff 1024 loff 63744

Use the foff (1024) as the offset to the next call to print with the -h option to display the field names and the -citdf options to display the change type, inode number, time stamp, directory inode number, and file name for each record.

# fcladm -h -citdf print 0x400 /export/data Change Type Inode Number Timestamp Dir Inode Number Filename Create 5 Thu Apr 10 13:49:54 2003 Extend 5 Thu Apr 10 13:50:02 2003 Create 6 Thu Apr 10 13:50:30 2003 Unlink 6 Thu Apr 10 13:50:38 2003 2 bar

Printing FCL Contents

When the FCL superblock is displayed using the print keyword, the output contains the following information:

o The magic number that identifies the FCL file. This is always a506fcf5.
o The version of the FCL file. This is either 3 or 4 for VxFS 5.0.
o The last time that the FCL was activated. This can be used by a script that scans the FCL periodically to check if the FCL has been active continuously since its last scan.
o The activation state of the FCL. If the state is ON, changes to the file system are logged in the FCL.
o The first and last valid offsets in the FCL: foff and loff. FCL records are present only between these offsets.
o The eventmask, which is a hexadecimal number representing the set of events being tracked. If the eventmask is interpreted as a 64-bit number and the event ’e’ is defined as ’20’ in the fcl.h header, the logging of event ’e’ is enabled when the 20th bit is set in the eventmask.
o The eventmask change time, which represents the time that the eventmask was last changed, that is, the time when the set of events was last changed through the set or clear keyword.
When a non-zero offset is specified with the print keyword, fcladm prints the contents of the FCL starting at the specified offset until the end of the file. The output consists of one physical FCL record per line, where each file system event corresponds to one or more physical FCL records. The output also shows the event type whether the tracking of additional information, such as access information, is enabled.
Each physical FCL record typically contains the following basic information:
o The change or event type.
o The inode number and generation count of the file or directory that was changed.
o The time when the event occurred.
FCL Event Types

Certain records have additional information that is specific to each event type. This information is either stored along with the base FCL record or as an extension record. The extension record is another physical FCL record that immediately follows the base record. For instance in the case of a file unlink, the name of the file that was unlinked and the inode number of the file directory is stored as a part of the unlink record. However, if the tracking of access information is enabled, the extra access information is stored as a separate FCL record that immediately follows the original record. For example, if accessinfo has been enabled, a file create results in a Create record followed by an AccessInfo record.

The following file system events produce an FCL record that contains only the basic information listed above. The change type is the string that is displayed by the print keyword.

--------------------------- ----------------- File system event type Change type --------------------------- ----------------- File create Create e.g. ls > newfile --------------------------- ----------------- File undelete through the Undelete VxFS internal file promote API. --------------------------- ------------------ Extending write to the file Extend i.e., one that increases the size of the file --------------------------- ------------------ Write to a file that Overwrite overwrites existing contents, but does not increase the file size --------------------------- ------------------ File truncates, i.e., Truncate operations that reduce the file size --------------------------- ------------------ Extended attribute change Ext_Attr_Chg --------------------------- ------------------ Operations that result in Hole_Punch deallocating some of the internal blocks of the file --------------------------- ------------------ Symbolic link creation Sym_Link e.g., ln -s file symlink --------------------------- ------------------ Inode extent attributes ExtnAttrChg change --------------------------- ------------------ Change in the number of ReserveChg blocks reserved to a file. The reservation can be set through the setext command. See the setext(1M) manual page. --------------------------- ------------------ File mode change. See the ModeChg chmod(1) manual page. --------------------------- ------------------- File owner change. See OwnerChg the chown(1) manual page. --------------------------- ------------------- File group change. See GroupChg the chgrp(1) manual page. --------------------------- ------------------- File modification time MtimeChg change. See the touch(1) manual page. --------------------------- -------------------

In addition, the following system events also contain this information:

o A file name.
o The inode number.
o The generation count of the directory containing the file name.

--------------------------- ----------------- File system event type Change type --------------------------- ----------------- Create a hard link to an Add_Link existing file. See the ln(1) manual page. This FCL record contains the file name and the directory inode number of the new link. --------------------------- ----------------- File removal or unlink via Unlink the rm(1) or unlink(2) manual pages. The directory information corresponds to the removed file. --------------------------- ----------------- Rename an existing file. Rename See the mv(1) manual page. This record contains the old file name. --------------------------- -----------------

In 5.0, the information maintained with each record and events cause the following records to be written:
FileOpen If the FileOpen event is enabled through the set keyword, every file open produces an FCL record, subject to the fcl_ointerval tunable. See the vxtunefs(1m) manual page. A file open record is displayed with the change type, FileOpen, followed by the inode number and generation count of the opened file, along with the time of the file opening and the process command name that opened the file.
FileStats This record contains the file I/O statistics that are periodically written to the FCL by VxFS. Apart from the basic information, each FileStats record contains the I/O statistics comprising the number of reads to the file, the number of writes, the number of blocks read, the number of blocks written, the average time for each read, and the average time for each write. This is followed by the last reset time, the node ID from where the statistics were written and the reset flag. The I/O statistics recorded in the FCL are cumulative from the last reset time to the next. The last reset time is updated each time the reset flag is set to 1.
  The FclEvntMask record is written to the FCL whenever the recording of a set of events is enabled or disabled through the set or clear keywords. The record contains two hexadecimal numbers that represent the old set of events and the new set of events. That is, the numbers represent the eventmask that was present in the FCL superblock before and after the set or clear operation.
AccessInfo When recording of access information is enabled through the set keyword, an AccessInfo record is written with each event logged in the FCL, immediately following the change record. The information printed for every AccessInfo record contains the real user ID, group ID of the process that performed the operation, the effective UID and group ID, followed by the node ID and the process ID. The AccessInfo record exists only as an extension record to some existing change type, but never independently. In addition, even if enabled, an AccessInfo record may not always be present for certain file system internal operations or when the access information is not available.

A call to fcladm print with just the offset and no extra options prints all the records in the FCL starting from that offset and all the information that is tracked with each record. However, new record types or information provided in a future VxFS release may not be available to an application or script that uses a Version 4 FCL. For compatibility, make sure that the script tries to interpret only the set of records enumerated in this man page and ignores other records.

Synchronizing the FCL

The following example provides a script that periodically scans the file system to determine the set of file changes since the last scan. The script performs the following tasks:

o Maintains a syncfile containing the synchronization offset from the last scan.
o Uses the offset in this file as the starting point for the current scan.
o Gets a synchronization point and updates the syncfile with this offset.

# Get the previous synchronization point stored in syncfile. # Set a synchronization point in the FCL and save the offset to # syncfile. Print records starting from previous sync offset. $ syncoffset=‘cat syncfile‘ $ fcladm sync /mnt1 > syncfile $ fcladm -citf print $syncoffset /mnt1 ModeChg 4 Thu 01 Jul 2004 12:51:10 AM Extend 4 Thu 01 Jul 2004 12:51:20 AM FileOpen 1071 Thu 01 Jul 2004 12:52:10 AM a.out

Interpreting the Contents of the FCL

FCL clients can use the information stored in the FCL to:

o Determine the full path name of every file changed in the file system, based on several categories of changes
o Determine whether an inode number was reused
o Determine the user and group names and obtain hostnames in a cluster configuration
To obtain the full file path name relative to the root of the file system, the inode number acquired from the FCL record must be passed to the VxFS Reverse Name Lookup (RNL) API. See the vxlsino(1M), vxfs_inotopath(3) and vxfs_inotopath_gen(3) manual pages. In cases where the file was renamed or removed, the directory inode number can be given to the RNL API to help obtain the full path name for the parent directory relative to the root of the file system. The file name stored in the FCL record can then be appended to this path to get the full file path name.

You can use the file generation count to determine whether an inode number was reused when another FCL record has the same inode number. However, you cannot use the file generation count to determine inode number reuse with the remove record. The generation count displayed in the remove record is the generation count of the directory inode and not of the inode that was removed.

Similarly, the user ID and group IDs displayed along in the AccessInfo records can be used in conjunction with the /etc/passwd file to determine the user and group names. The node ID printed with this record is important only in clusters configurations. With this information, you can use the lltstat command to obtain the hostname in a cluster.


lost+found/changelog The FCL file.
/opt/VRTS/include/sys/fs/fcl.h The header file containing the data structures and definitions used by the FCL.
/etc/vx/tunefstab VxFS tuning parameters table.


vxlsino(1M), vxtunefs(1M), vxfs_fcl_sync(3), vxfs_inotopath(3), vxfs_inotopath_gen(3), tunefstab(4), vxfsio(7)

VxFS 8.0 fcladm(1M)