--- a/userlibandfileserver/fileserver/inc/f32file.h Thu May 27 14:17:14 2010 +0300
+++ b/userlibandfileserver/fileserver/inc/f32file.h Fri Jun 11 15:02:23 2010 +0300
@@ -708,27 +708,28 @@
{
public:
/**
- 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.
+ The size of a media block in bytes. This is a physical property of a media and returned by the corresponding media driver.
+ This value is usually at least 512 bytes and always a power of 2. For some media types the meaning of this value is
+ "the min. size of the aligned data buffer which write onto the media doesn't lead to read-modify-write operation."
+ Therefore, reads and writes that are aligned on block boundaries and with lenght of a multiple block size can be much faster.
+ 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 iBlockSize;
+
/**
- 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.
+ The size in bytes of a single file system cluster. This is a logical property of the file system.
+ The file system organises and allocates the data on the disk in clusters where each cluster usually consists of one or more blocks.
+ Cluster is a minimal unit that the file system allocates on the volume. Thus, a file of 1 byte length occupies 1 cluster.
+
+ Read and write operations that are aligned on cluster boundaries are more efficient from the file system point of view.
+ In some circumstances cluster size can be less than a block size, but it is very inefficient.
+
+ This value is reported by a file system. The value less than 0 indicates a error.
*/
TInt iClusterSize;
+
+
/**
The recommended buffer size for optimised reading performance.
@@ -763,7 +764,7 @@
/**
The maximum file size that is supported by the file system mounted on this volume.
- Not all file system may provide this parameter; The value KMaxTUint64 (0xffffffffffffffff) means that this particular file system hasn't
+ Not all file system may report this parameter; The value KMaxTUint64 (0xffffffffffffffff) means that this particular file system hasn't
provided this information.
*/
TUint64 iMaxSupportedFileSize;