What is Oracle Exadata ?
Oracle Exadata Architecture
server communication,Administrative Ethernet switch for remote management
Oracle exadata Database Servers or Compute Nodes
2)Database Servers Runs Linux or Solaris and Oracle Database software
3) Perform complex database processing such as joins, aggregation, etc.
Oracle exadata Storage Servers or Cell servers
2)Search tables and indexes filtering out data not relevant to a query
3)Cells serve data to multiple databases enabling OLTP and consolidation
4)Simplicity, and robustness of storage appliance
There are mainly three services which run on cell server for processing, CellSRV (Cell Service), MS (Management Server) and RS (Restart Server).It has three components
1) CELLSRV, the cell service. CELLSRV handles the actual I/O processing of the storage server.
It is not uncommon to see heavy usage from CELLSRV process threads during periods of heavy load.
CELLSRV provides Communication with database nodes using the iDB/RDS protocols over the InfiniBand network,Disk I/O with the underlying cell disks
,Offload of SQL processing from database nodes ,I/O resource management, prioritizing I/O requests based on a defined policy
2)Management Server (MS): MS service provide an interface to DBA for communicating or Managing Cell Server. CellCLI is the Command Line tool which Exadata DBA used for performing Exadata Administration services. MS is written in Java, unlike the other background processes which are distributed in binary form and are likely written in C.
3) Restart Server (RS): This service is to make sure the functioning of Exadata Server. RS monitors CellSRV and MS for liveliness and restart them whenever required.
RS, the restart service. Performing a similar role to SMON, RS monitors other processes, and automatically restarts them if they fail unexpectedly.
RS also handles planned restarts in conjunction with software updates.
The main cellrssrm process spawns several helper processes, including cellrsbmt, cellrsbkm, cellrsomt, and cellrsssmt.
Most Useful features of Oracle Exadata
Suppose a simple query Select * from jtf_notes where jtt_type=’EXACT’ which returns only 10,0000 is executed on the database machine and the jtf_notes table has 1000 Million rows. So, in that case whole 1000 Million rows will come from Storage server to DB node for processing and after processing by DB node DBA will get query output. This whole process take lot of time and resources from all RAC components.Exadata smart scan returns only the 10,0000 rows to the database server . DBA can easily estimate the impact of this change. Technically this term is called as Exadata Smart Scan.
init ora parameter Cell_offload_processing controls
Default setting is true. We can manipulate to find out if smart scan is causing any issue
2) Exadata Storage Indexes – Eliminate unnecessary I/Os. Storage cells keep track on maximum and minimum values stored in different areas and use those values to determine where predicates can not exist. This allows the storage cell to not have to read the area at all thus saving time and processing cycles.
3) Hybrid Columnar Compression – Oracle exadata architecture offers Efficient compression increases effective storage capacity and increases user data scan bandwidths by a factor of up to 10X
4) Exadata Smart Flash Cache – Oracle exadata architecture Breaks random I/O bottleneck by increasing IOPs by up to 20X; Doubles user data scan bandwidths
5) I/O Resource Manager (IORM) – Oracle exadata architecture Enables storage grid by prioritizing I/Os to ensure predictable performance
Cell Check and shutdown/startup commands:
cellcli -e alter cell startup services all
cellcli -e alter cell shutdown services cellsrv
cellcli -e alter cell restart services cellsrv
cellcli -e list lun detail
cellcli -e list griddisk detail
cellcli -e list celldisk detail
cellcli -e list physicaldisk detail
cellcli -e list flashcache detail
cellcli -e list physicaldisk attributes name, diskType, luns, status
cellcli -e list physicaldisk where disktype=harddisk attributes physicalfirmware
cellcli -e list lun attributes name, diskType, isSystemLun, status
service celld status (root/sudo)
lsscsi | grep MARVELL
Cell related Database view’s:
select * from sys.GV_$CELL;
select * from sys.GV_$CELL_THREAD_HISTORY;
select * from sys.GV_$CELL_REQUEST_TOTALS;
select * from sys.GV_$CELL_CONFIG;With Oracle Exadata Database Machine, customers can reduce IT costs through consolidation, manage more data on multiple compression tiers, improve performance of all applications, and make better business decisions in real time