A.15 I/O Write Commands

Use the commands in this section to control the write behavior of dirty blocks from the cache to the disk. These commands are available for OES 2 and later. For more information about using these commands, see Section 28.3, Configuring or Tuning Group I/O.

nss /JournalGroupWriteTime=seconds

Specify the elapsed time to wait before group writes of journal blocks.

Replace seconds with the maximum number of seconds to elapse before forcing journal blocks to be written to the volume. The default value of seconds is 1.

Example

To group write journal blocks every 2 seconds, enter

nss /Journal GroupWriteTime=2
nss /MetadataGroupWriteTime=seconds

Specify the elapsed time to wait before group writes of metadata blocks. Decreasing the metadata group write timer can help reduce the mount time for the volume after a crash.

Replace seconds with the maximum number of seconds to elapse before forcing metadata blocks to be written to the volume. The default value of seconds is 40.

Example

To group write metadata blocks every 30 seconds, enter

nss /MetadataGroupWriteTime=30
nss /UserDataGroupWriteTime=seconds

Specify the elapsed time to wait before group writes of user data blocks. Decreasing the user data group write timer can help reduce the risk of data loss for a volume after a crash.

Replace seconds with the maximum number of seconds to elapse before forcing user data blocks to be written to the volume. The default value of seconds is 3.

Example

To group write user data blocks every 1 second, enter

nss /UserDataGroupWriteTime=1
nss /MetadataGroupWriteLimit=blocks

Specify the maximum number of metadata blocks that can be dirty before a group write is performed.

Replace blocks with the maximum number of metadata blocks that can be dirty before forcing them to be written to the volume. The default value of blocks is 20000.

Examples

To decrease the maximum number of dirty metadata blocks to 15,000 for the purpose of reducing the mount time, enter

nss /MetadataGroupWriteLimit=15000

To increase the maximum number of dirty metadata blocks to 30,000 for the purpose of increasing the file system performance, enter

nss /MetadataGroupWriteLimit=30000
nss /FastWriteOfMessyBeasts

This enables or disables the fast update of messy files.

Example

To disable the fast update of messy files, enter

nss /NoFastWriteOfMessyBeasts

To enable the fast update of messy files, enter

nss /FastWriteOfMessyBeasts