Interleaved Grid Disks

10.7.5 Interleaved Grid Disks

This feature is deprecated in Oracle Exadata System Software release 19.1.0.

Space for grid disks can be allocated in an interleaved manner. Grid disks that use this type of space allocation are referred to as interleaved grid disks. This method attempts to equalize the performance of the grid disks residing on the same cell disk rather than having the grid disks that occupy the outer tracks getting better performance at the expense of the grid disks on the inner tracks.

A cell disk is divided into two equal parts, the outer half (upper portion) and the inner half (lower portion). When a new grid disk is created, half of the grid disk space is allocated on the outer half of the cell disk, and the other half of the grid disk space is allocated the inner half of the cell disk. The upper portion of the grid disk starts on the first available outermost offset in the outer half depending on free or used space in the outer half. The lower portion of the grid disk starts on the first available outermost offset in the inner half.

For example, if cell disk, CD_01_cell01 is completely empty and has 100 GB of space, and a grid disk, data_CD_01_cell01, is created and sized to 50 GB on the cell disk, then the cell disk would have the following layout:

- Outer portion of data_CD_01_cell01 - 25GB
- Free space - 25GB
------------ Middle Point ------------------
- Inner portion of data_CD_cell01 - 25GB
- Free space - 25GB