Class TVolumeIOParamInfo

class TVolumeIOParamInfo;

Description

Volume IO parameter information.

This class is used to return IO parameter information for a specified volume.

The volume parameter information holds recommended buffer sizes for the creation of efficient buffers for reading and writing.

Members

Defined in TVolumeIOParamInfo:

• iBlockSizeThe size of a block in bytes
• iClusterSizeThe size in bytes of a single disk cluster
• iRecReadBufSizeThe recommended buffer size for optimised reading performance
• iRecWriteBufSizeThe recommended buffer size for optimised writing performance

See also:

• RFs::VolumeIOParam()This function queries a set of I/O parameters on the specified volume, this includes the block size of underlying media, cluster size of the mounted file system and the recommended read/write buffer sizes

TInt iBlockSize;

Description

The size of a block in bytes.

Reads and writes that are aligned on block boundaries are up to twice as fast as when mis-aligned.

Read and write operations on certain underlying media is done in blocks. A write operation that modifies only part of a block is less efficient, in general, than one that modifies an entire block. Data throughput degrades linearly for reads and writes in smaller sized units.

TInt iClusterSize;

Description

The size in bytes of a single disk cluster.

Read and write operations that are aligned on cluster boundaries are more efficient.

The file system organises and allocates the file data on the disk in clusters where each cluster is one or more blocks. Files that are not zero length occupy at least one cluster of the disk, so large numbers of very small files use up more disk space than expected.

TInt iRecReadBufSize;

Description

The recommended buffer size for optimised reading performance.

The given buffer size is based on sensible benchmark testing results produced by the mobile device vendor. The buffer size is then added to the estart.txt file

The figure is included in the estart.txt file along with the drive number and the variable name. The example below shows the required format:

[DriveC] RecReadBufSize 8192

When no value is provided, value KErrNotSupported is returned.

TInt iRecWriteBufSize;

Description

The recommended buffer size for optimised writing performance.

The given buffer size is based on sensible benchmark testing results produced by the mobile device vendor. The buffer size is then added to the estart.txt file

The figure is included in the estart.txt file along with the drive number and the variable name. The example below shows the required format:

[DriveC] RecWriteBufSize 16384

When no value is provided, value KErrNotSupported is returned.