READ and WRITE operations use an array of scatter/gather descriptors to describe the buffer space to be used in the operation. This enables transfers of contiguous disk blocks into physically discontiguous, byte-aligned memory blocks. Scatter/gather descriptors have the following format:

┌──────────────────────────────┬──────────────────────────────┐
│Field                         │Length                        │
├──────────────────────────────┼──────────────────────────────┤
│BufferPtr                     │DWORD                         │
├──────────────────────────────┼──────────────────────────────┤
│Buffer Size                   │DWORD                         │
└──────────────────────────────┴──────────────────────────────┘

BufferPtr

A 32-bit physical pointer to the buffer
Buffer Size
Size of the buffer in bytes

---

[Back: Write/Read/WriteVerify]
[Next: READ PREFETCH]