mount.ocfs2

Section: OCFS2 Manual Pages (8)
Updated: January 2012
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NAME

mount.ocfs2 - mount an OCFS2 filesystem

SYNOPSIS

mount.ocfs2 [-vn] [-o options] device dir

DESCRIPTION

mount.ocfs2 mounts an OCFS2 filesystem at dir. It is usually invoked indirectly by the mount(8) command.

OPTIONS

_netdev

Indicates that the file system resides on a device that requires network access (used to prevent the system from attempting to mount these filesystems until the network has been enabled on the system). mount.ocfs2(8) transparently appends this option during mount. However, users mounting the volume via /etc/fstab must explicitly specify this mount option to delay the system from mounting the volume until after the network has been enabled.

noatime

The file system will not update access time.

relatime

The file system will update atime only if the on-disk atime is older than mtime or ctime.

strictatime,atime_quantum=nrsec

The file system will always perform atime updates, but the minimum update interval is specified by atime_quantum which defaults to 60 secs. Set it to zero to always update atime. These two options need work together.

[no]acl

Enables / disables POSIX ACLs (access control lists) support.

[no]user_xattr

Enables / disables extended user attributes.

commit=nrsec

Sync all data and metadata every nrsec seconds. The default value is 5 seconds. Zero means default.

data=[ordered|writeback]

Specifies the handling of file data during metadata journalling.

ordered: This is the default mode. Data is flushed to disk before the corresponding meta-data is committed to the journal.
writeback: Data ordering is not preserved - data may be flushed to disk after the corresponding meta-data is committed to the journal. This is rumored to be the higher-throughput option. While it guarantees internal file system integrity, it can allow old data to appear in files after a crash and journal recovery.

errors=[remount-ro|errors=panic|errors=continue]

Specifies the behavior when an on-disk corruption is encountered.

remount-ro: This is the default mode. The file system is remounted read-only.
panic: The system is halted via panic.

continue: Ignore errors. Just log error message, return error code to the calling process and continue.

localflocks

This disables cluster-aware flock(2).

coherency=[full|coherency]

Specifies the extent of coherency for the cached file data across the cluster. This mount option works with Linux kernel 2.6.37 and later.

full: This is the default mode. The file system ensures the cached file data is coherent across the cluster for all IO modes.
buffered: The file system only ensures the cached file data coherency for buffered mode IOs. It does not perform IO serialization for direct IOs. This allows multiple nodes to perform concurrent direct IOs to the same file. This is the recommended mode for volumes hosting database files.

resv_level=level

Specifies the level of allocation reservation for files. The higher the value, the more aggressive it is. Valid values are between 0 (reservation off) to 8 (maximum space for reservation). It defaults to 2. This mount option works with Linux kernel 2.6.35 and later.

dir_resv_level=level

By default, directory reservation scales with file reserveration. Users should rarely need to change this value. If the file allocation reservation is turned off, this option will have no effect. This mount option works with Linux kernel 2.6.35 and later.

inode64

Indicates that the file system can create inodes at any location in the volume, including those which will result in inode numbers greater than 4 billion.

[no]intr

Specifies whether a signal can interrupt IOs. It is disabled by default.

ro

Mount the file system read-only.

rw

Mount the file system read-write.

NOTES

To mount and umount a OCFS2 volume, do:

# mount /dev/sda1 /mount/path
 ...
# umount /mount/path

Users mounting a clustered volume should be aware of the following:

1. The cluster stack must to be online for a clustered mount to succeed.

2. The clustered mount operation is not instantaneous; it must wait for the node to join the DLM domain.

3. Likewise, clustered umount is also not instantaneous; it involves migrating all mastered lock-resources to the other nodes in the cluster.

If the mount fails, detailed errors can be found via dmesg(8). These might include incorrect cluster configuration (say, a missing node or incorrect IP address) or a firewall interfering with o2cb network traffic. Check the configuration as listed in o2cb(7) or the man page of the active cluster stack.

To auto-mount volumes on startup, the file system tools include an ocfs2 init service. This runs after the o2cb init service has started the cluster. The ocfs2 init service mounts all OCFS2 volumes listed in /etc/fstab.

# chkconfig --add o2cb
o2cb 0:off 1:off 2:on 3:on 4:off 5:on 6:off

$ chkconfig --add ocfs2
o2cb 0:off 1:off 2:on 3:on 4:off 5:on 6:off

$ cat /etc/fstab
 ...
/dev/sda1     /u01     ocfs2     _netdev,defaults     0  0
 ...

AUTHORS

Oracle Corporation