Overview

In this section we will configure and manage the Exadata storage cells. In exadata the storage cells are separate servers with their own operation system, mini oracle database and of course a storage. The facilitate the smart scan capabilities of exadata, by being able to scan through an oracle block and provide ONLY the necessary rows to a server process. Since they provide only the rows, that information cannot “live” in the SGA, but only in the PGA.

Configuration

Management

List Cell Processes

The storage cell server has couple processes:

RS (Restart Server) - Used to start and shut down the Cell server (cellsrv) and Management Server (MS)

MS (Management Server) - Provides exadata cell management and configuration. Cooperates with the cellcli interface. Also send alerts and gather statistics in addition to these collection by the cellsrv

Cellsrv (Cell server) - Primary exadata component, provides most of the exadata storage services. Primary Cellsrv communicates with the oracle database in order to provide simple block requests or smart-scan capabilities. It also implements IO management (IORM) and collects numerous statistics.

RS Server

MS Server

CellSRV

it is important to note that both: MS and CellSRV are children of the RS server (they have RS as a parent).

Examine storage Cell

With the cellCli we can also list the storage cell Luns. P.S. Since I don't have money for real exadata there will be some discrepencies between my output and the real output which you will get in the real exadata: Each exadata consists of:

12 Hard disk based Luns

4 Flash based Luns

Let's firstly start with the examination of tha Hard disk based storage:

Hard Disk Based

To list the status of a storage cell server, we can use the following command:

We can obtain more detailed information using the cellCli interface:

List Lun

The result which you will get on the real exadata will be similary to:

The reason for that is the fact that on my virtualized env, the Cells are mapped to a virtualized disks and virtualized flash devices, where on real exadata, they will be mapped to PCI slot and device number.

We can list a specific LUN in more details, as follows:

List Lun

List Physical Disk

List celldisk

List grid disk

Flash Based

The flash based modules, can be examined as the hard disk based ones:

List the cell disks

Apart from the flashdisk, the exadata has also flashlog, to improve the redo log latency.

Flash log

Stop / Start Cell Services

We can Restart all cell services using the cellCli interface as follows:

This action, will NOT cause downtime.