gpfsGetDataBlkDiskIdx_t structure

Library

GPFS Library (libgpfs.a for AIX®, libgpfs.so for Linux®)

Structure

typedef struct {
  int structLen;
  int structType;
  FilemapIn filemapIn;
  FilemapOut filemapOut;
} gpfsGetDataBlkDiskIdx_t;

Description

The gpfsGetDataBlkDiskIdx_t structure is used to obtain a file's blocks on-disk or in-memory location information.

Members

structLen

Length of the gpfsGetDataBlkDiskIdx_t structure.

structType

The structure identifiers are GPFS_FCNTL_GET_DATABLKDISKIDX and GPFS_FCNTL_GET_DATABLKLOC. GPFS_FCNTL_GET_DATABLKDISKIDX can be used to retrieve the disk ID on which the data blocks are located. GPFS_FCNTL_GET_DATABLKLOC can be used to retrieve the disk ID on which the data blocks are located and the node ID on which data block buffers (in memory) are located.

filemapIn

Input parameters:

struct FilemapIn {
    long long startOffset;
    long long skipfactor;
    long long length;
    int mreplicas;
    int reserved;
  } FilemapIn;

startOffset

Start offset in bytes.

skipfactor

Number of bytes to skip before the next offset read. Could be 0 in which case the meta block size will be used as the skipfactor.

length

Number of bytes to read; startOffset + length / skipfactor = numBlksReturned

mreplicas

Number of replicas that the user wants.

0 - all; 1 - primary; 2 - primary and 1st replica; 3 - primary, 1st and 2nd replica

reserved

Reserved field that should not be used.

filemapOut

Output data:

struct FilemapOut {
    int numReplicasReturned;
    int numBlksReturned;
    int blockSize;
    int blockSizeHigh;
    char buffer [GPFS_MAX_FCNTL_LENGTH-1024];
  } FilemapOut;

numReplicasReturned

Number of replicas returned.

numBlksReturned

Number of data blocks returned.

blockSize

Low 32bits of meta block size. Only valid if skipfactor in the input is 0. Otherwise, blockSize will be 0.

blockSizeHigh

High 32bits of meta block size. Only valid if structType is GPFS_FCNTL_GET_DATABLKLOC and skipfactor in the input is 0. Otherwise, blockSizeHigh will be 0.

buffer [GPFS_MAX_FCNTL_LENGTH-1024]

Buffer in which the disk ID and node ID are stored. If the buffer cannot store all of the requested information, you will have to calculate a new startOffset and length in the input data according to the output data and then repeat the call.

If structType is GPFS_FCNTL_GET_DATABLKDISKIDX, the format is:

If number of replicas returned is 1,
      offset(64bits) disid1(32bits)
      offset(64bits) diskid1(32bits)
      ...
      If number of replicas returned is 2,
      offset(64bits) diskid1(32bits) diskid2(32bits)
      offset(64bits) diskid1(32bits) diskid2(32bits)
      ...
      If number of replicas returned is 3,
      offset(64bits) diskid1(32bits) diskid2(32bits) diskid3(32bits)
      offset(64bits) diskid1(32bits) diskid2(32bits) diskid3(32bits)
      ...

If structType is GPFS_FCNTL_GET_DATABLKLOC, the format is:

If number of replicas returned is 1,
      disid1(32bits) nodeid1(32bits)
      disid1(32bits) nodeid1(32bits)
      ...
      If number of replicas returned is 2,
      disid1(32bits) diskid2(32bits) nodeid1(32bits) nodeid2(32bits)
      disid1(32bits) diskid2(32bits) nodeid1(32bits) nodeid2(32bits)
      ...
      If number of replicas returned is 3,
      disid1(32bits) diskid2(32bits) diskid3(32bits) nodeid1(32bits) nodeid2(32bits)
       nodeid3(32bits)
      disid1(32bits) diskid2(32bits) diskid3(32bits) nodeid1(32bits) nodeid2(32bits)
       nodeid3(32bits)
      ...

Location

/usr/lpp/mmfs/lib/libgpfs.a for AIX

/usr/lpp/mmfs/lib/libgpfs.so for Linux