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Oracle

Posted December 9, 2013

Oracle Exadata: DMA or DBA

By David Fitzjarrell

Exadata is a different system for a DBA to administer. Some tasks in this environment, such as running the exachk script, require root O/S privileges. This script can be run by the system administrator, and this will be the case if you are managing Exadata as a DBA. However, a new role has emerged relative to Exadata, that of the Database Machine Administrator, or DMA. Let's look at what being a DMA really means.

In addition to the usual DBA skillset, the DMA must also be familiar with, and be able to understand, the following management and monitoring commands on the specified systems. On the compute nodes (database nodes):

Linux:   top , mpstat , vmstat , iostat , fdisk , ustat , sar , sysinfo 
Exadata:   dcli 
ASM:   asmcmd , asmca 
Clusterware:   crsctl , srvctl

On the storage servers/cells:

Linux:   top , mpstat , vmstat , iostat , fdisk , ustat , sar , sysinfo 
Cell   management: cellcli , cellsrvstat 

Being a DMA also includes other areas of responsibility not associated with being a DBA. The following table summarizes the areas of responsibility for a DMA:

 

 

DMA Responsibilities

Skill Percent

System Administrator

15

Storage Administrator

0

Network Administrator

5

Database Administrator

60

Cell Administrator

20

The "Percent" column indicates the percentage of the overall Exadata system requiring this knowledge, and as you can see if you've been an 11g RAC administrator, you have 60 percent of the skillset required to be a DMA. The remaining skills necessary to be a DMA are not difficult to learn and master. The Cell Administrator commands you will need ( cellcli , dcli ) will increase your knowledge to 80 percent of the DMA skillset. CellCLI is the command-line interface to monitor and manage the storage cells. There are three supplied logins to each storage cell and these are 'root', 'cellmonitor' and 'celladmin'. As you can probably guess 'celladmin' is the most powerful login that isn't 'root' (the superuser in Linux and Unix). You can do most anything to the storage cells, including startup and shutdown, with 'celladmin'. The 'cellmonitor' user can generate reports and list attributes from the storage cells but has no authority to perform management tasks. The full list of available cellcli commands is shown below:

CellCLI>   help
 
 HELP   [topic]
     Available Topics:
          ALTER
          ALTER ALERTHISTORY
          ALTER CELL
          ALTER CELLDISK
          ALTER GRIDDISK
          ALTER IBPORT
          ALTER IORMPLAN
          ALTER LUN
          ALTER PHYSICALDISK
          ALTER QUARANTINE
          ALTER THRESHOLD
          ASSIGN KEY
          CALIBRATE
          CREATE
          CREATE CELL
          CREATE CELLDISK
          CREATE FLASHCACHE
          CREATE FLASHLOG
          CREATE GRIDDISK
          CREATE KEY
          CREATE QUARANTINE
          CREATE THRESHOLD
          DESCRIBE
          DROP
          DROP ALERTHISTORY
          DROP CELL
          DROP CELLDISK
          DROP FLASHCACHE
          DROP FLASHLOG
          DROP GRIDDISK
          DROP QUARANTINE
          DROP THRESHOLD
          EXPORT CELLDISK
          IMPORT CELLDISK
          LIST
          LIST ACTIVEREQUEST
          LIST ALERTDEFINITION
          LIST ALERTHISTORY
          LIST CELL
          LIST CELLDISK
          LIST FLASHCACHE
          LIST FLASHCACHECONTENT
          LIST FLASHLOG
          LIST GRIDDISK
          LIST IBPORT
          LIST IORMPLAN
          LIST KEY
          LIST LUN
          LIST METRICCURRENT
          LIST METRICDEFINITION
          LIST METRICHISTORY
          LIST PHYSICALDISK
          LIST QUARANTINE
          LIST THRESHOLD
          SET
          SPOOL
          START
 
CellCLI>

All of the above commands are available to 'celladmin'; only the LIST, DESCRIBE, SET and SPOOL commands are available to 'cellmonitor'.

Networking commands that you may need are ifconfig , iwconfig , netstat , ping , traceroute , and tracepath . You may, at some time, also need ifup and ifdown , to bring up or bring down network interfaces, although using these commands will not be a regular occurrence. The following example shows how to bring up the eth0 interface.

# ifup eth0

It seems like a daunting task, to become a DMA, but it really isn't that difficult. It does require a slightly different mindset, as you are now looking at, and managing, the entire system, rather than just the database. There will still be a need for a dedicated System Administrator and Network Administrator for your Exadata system, because, as a DMA, you won't be responsible for configuration of these resources, nor will you be responsible for patching and firmware upgrades. The DMA is, essentially, assisting these dedicated administrators by assuming the day-to-day tasks these resources would provide. Being a DMA is also more useful to you and to the enterprise as the regular tasks for these areas can be performed by the person or persons who do most of the interaction with Exadata on a daily basis. Enterprises vary, however, and it may not be possible to assume the role of DMA as the division of duties is strictly outlined and enforced. It is good to know, though, that such a role exists and may be made available to you at some time in the future.

See all articles by David Fitzjarrell



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