martes, 21 de agosto de 2012

Allocation Pages


Allocation pages are special pages in the data files that track and mange extent allocations. There are 3 types.

Global Allocation Map (GAM): Tracks which extents have been allocated. There is 1 GAM page for every 4 GB of data file. It is always page 2 in the data file and then repeats every 511,232 pages.

Shared Global Allocation Map (SGAM): Tracks which extents are being used as mixed (shared) extents. There is 1 SGAM page for every 4 GB of data file. It is always page 3 in the data file and then repeats every 511,232 pages.

Page Free Space (PFS): Tracks the allocation status of each page and approximately how much free space it has. There is 1 PFS page for every 1/2 GB of data file. It is always page 1 in the data file and then repeats every 8,088 pages.

No hay comentarios:

Publicar un comentario