The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.
You can use the mkfs.ocfs2 command to create an OCFS2 volume on a device. If you want to label the volume and mount it by specifying the label, the device must correspond to a partition. You cannot mount an unpartitioned disk device by specifying a label. The following table shows the most useful options that you can use when creating an OCFS2 volume.
Command Option | Description |
|---|---|
-b
--block-size
| Specifies the unit size for I/O transactions to and from the file system, and the size of inode and extent blocks. The supported block sizes are 512 (512 bytes), 1K, 2K, and 4K. The default and recommended block size is 4K (4 kilobytes). |
-C
--cluster-size
| Specifies the unit size for space used to allocate file data. The supported cluster sizes are 4K, 8K, 16K, 32K, 64K, 128K, 256K, 512K, and 1M (1 megabyte). The default cluster size is 4K (4 kilobytes). |
--fs-feature-level= | Allows you select a set of file-system features:
|
--fs_features= |
Allows you to enable or disable individual features
such as support for sparse files, unwritten extents,
and backup superblocks. For more information, see
the |
-J
size=
--journal-options
size= |
Specifies the size of the write-ahead journal. If
not specified, the size is determined from the file
system usage type that you specify to the
-T option, and, otherwise, from
the volume size. The default size of the journal is
64M (64 MB) for |
-L
--label
| Specifies a descriptive name for the volume that allows you to identify it easily on different cluster nodes. |
-N
--node-slots
| Determines the maximum number of nodes that can concurrently access a volume, which is limited by the number of node slots for system files such as the file-system journal. For best performance, set the number of node slots to at least twice the number of nodes. If you subsequently increase the number of node slots, performance can suffer because the journal will no longer be contiguously laid out on the outer edge of the disk platter. |
-T
| Specifies the type of usage for the file system:
|
For example, create an OCFS2 volume on
/dev/sdc1 labeled as myvol
using all the default settings for generic usage (4 KB block and
cluster size, eight node slots, a 256 MB journal, and support
for default file-system features).
# mkfs.ocfs2 -L "myvol" /dev/sdc1
Create an OCFS2 volume on /dev/sdd2 labeled
as dbvol for use with database files. In this
case, the cluster size is set to 128 KB and the journal size to
32 MB.
# mkfs.ocfs2 -L "dbvol" -T datafiles /dev/sdd2
Create an OCFS2 volume on /dev/sde1 with a 16
KB cluster size, a 128 MB journal, 16 node slots, and support
enabled for all features except refcount trees.
#mkfs.ocfs2 -C 16K -J size=128M -N 16 --fs-feature-level=max-features\--fs-features=norefcount /dev/sde1
Do not create an OCFS2 volume on an LVM logical volume. LVM is not cluster-aware.
You cannot change the block and cluster size of an OCFS2
volume after it has been created. You can use the
tunefs.ocfs2 command to modify other
settings for the file system with certain restrictions. For
more information, see the tunefs.ocfs2(8)
manual page.
If you intend the volume to store database files, do not specify a cluster size that is smaller than the block size of the database.
The default cluster size of 4 KB is not suitable if the file system is larger than a few gigabytes. The following table suggests minimum cluster size settings for different file system size ranges:
File System Size | Suggested Minimum Cluster Size |
|---|---|
1 GB - 10 GB | 8K |
10GB - 100 GB | 16K |
100 GB - 1 TB | 32K |
1 TB - 10 TB | 64K |
10 TB - 16 TB | 128K |