Exadata使用技巧 (-)

Posted 2020-09-06

1. 概述

Exadata数据库一体机已经经过多年的风雨磨砺修炼为X6版本；在中国Exadata也有着众多的成功案例，基于Oracle原厂和众多服务商的努力，我们对Exadata的使用也越来越成熟。 以下是常用的使用技巧，供大家参考。

 

2. Exadata管理

2.1 Exadata性能优化

让表使用flash cache

ALTER TABLE <object name> storage (CELL_FLASH_CACHE KEEP);

可以使用如下公式计算Exadata特性对IO的优化

[ 1 – {(cell physical IO interconnect bytes returned by smart scan) / (cell IO uncompressed bytes + cell physical IO bytes saved by storage index)} ] * 100

可以使用如下公式计算Exadata Storage Index对Disk IO减少的共享

(cell physical IO bytes saved by storage index / physical read total bytes) * 100

可以使用如下计算Flash Cache的使用率

(cell flash cache read hit / physical read total IO requests) * 100

2.2 收集cell级别的表缓存统计信息的方法

收集cell级别的表缓存统计信息的方法

SQL> SELECT data_object_id FROM DBA_OBJECTS WHERE object_name=’EMP’;

OBJECT_ID

———

57435

CellCLI> LIST FLASHCACHECONTENT –

WHERE objectNumber=57435 DETAIL cachedSize: 495438874

dbID: 70052

hitCount: 415483

missCount: 2059

objectNumber: 57435

tableSpaceNumber: 1

2.3 使用write back flash cache

#dcli -g ~/cell_group -l root cellcli -e “list cell attributes flashcachemode”

Results:

flashCacheMode: WriteBack -> write back flash cache is enabled

flashCacheMode: WriteThrough -> write back flash cache is not enabled

2.4 确认griddisk和flashdisk状态

确认所有的griddisk均为正常online状态

# dcli -g cell_group -l root cellcli -e list griddisk attributes asmdeactivationoutcome, asmmodestatus

确认所有的flashdisk均为正常online状态

# dcli -g cell_group -l root cellcli -e list flashcache detail

2.5 启用write back flash cache

A. Enable Write Back Flash Cache using a ROLLING method

(RDBMS & ASM instance is up – enabling write-back flashcache one cell at a time)

Log onto the first cell that you wish to enable write-back FlashCache

1. Drop the flash cache on that cell

# cellcli -e drop flashcache

2. Check if ASM will be OK if the grid disks go OFFLINE. The following command should return ‘Yes’ for the grid disks being listed:

# cellcli -e list griddisk attributes name,asmmodestatus,asmdeactivationoutcome

3. Inactivate the griddisk on the cell

# cellcli –e alter griddisk all inactive

4. Shut down cellsrv service

# cellcli -e alter cell shutdown services cellsrv

5. Set the cell flashcache mode to writeback

# cellcli -e “alter cell flashCacheMode=writeback”

6. Restart the cellsrv service

# cellcli -e alter cell startup services cellsrv

7. Reactivate the griddisks on the cell

# cellcli –e alter griddisk all active

8. Verify all grid disks have been successfully put online using the following command:

# cellcli -e list griddisk attributes name, asmmodestatus

9. Recreate the flash cache

# cellcli -e create flashcache all

10. Check the status of the cell to confirm that it’s now in WriteBack mode:

# cellcli -e list cell detail | grep flashCacheMode

11. Repeat these same steps again on the next cell. However, before taking another storage server offline, execute the following making sure ‘asmdeactivationoutcome’ displays YES:

# cellcli -e list griddisk attributes name,asmmodestatus,asmdeactivationoutcome

B . Enable Write Back Flash Cache using a NON-ROLLING method

(RDBMS & ASM instances are down while enabling write-back flashcache)

1. Drop the flash cache on that cell

# cellcli -e drop flashcache

2. Shut down cellsrv service

# cellcli -e alter cell shutdown services cellsrv

3. Set the cell flashcache mode to writeback

# cellcli -e “alter cell flashCacheMode=writeback”

4. Restart the cellsrv service

# cellcli -e alter cell startup services cellsrv

5. Recreate the flash cache

# cellcli -e create flashcache all

2.6 exadata计算节点网络带宽

确认Exadata 计算节点间的网络带宽

可以采用nc nc-1.84-10.fc6.x86_64.rpm获得

2.7 检查RDS是否可用

检测多个ORACLE_HOME是否RDS可用？

dcli -g /opt/oracle.SupportTools/onecommand/dbs_group -l oracle md5sum ${ORACLE_HOME}/lib/libskgxp11.so

relink ORACLE_HOME的RDS

dcli -g /opt/oracle.SupportTools/onecommand/dbs_group -l oracle “export ORACLE_HOME=$ORACLE_HOME;;cd `pwd`;;make – f i*mk ipc_rds”

dcli -g /opt/oracle.SupportTools/onecommand/dbs_group -l oracle “export ORACLE_HOME=$ORACLE_HOME;;cd `pwd`;;make – f i*mk ioracle” | egrep ‘rm|mv.*oracle‘

2.8 Exadata最大并行度

配置 CPU个数 推荐最大Parallelism

Full Rack 64 core DOP=256

Half Rack 32 core DOP=128

Quarter Rack 16 core DOP=64

2.9 Exadata EHCC支持

Exadata的EHCC支持宽表 最大支持1000个字段的表，而不像11.1中的压缩仅支持最多255列的表

2.10 Exadata 压缩信息

通过dbms_compression.get_compression_ratio 可以获得表的压缩信息

2.11 启用Smart Flash logging特性

针对写日志redo特别多的应用建议启用Smart Flash logging特性

CREATE FLASHLOG ALL

CREATE FLASHLOG ALL SIZE=1G

CREATE FLASHLOG CELLDISK=’fd1,fd2′

CREATE FLASHLOG CELLDISK=’fd1,fd2′ SIZE=1G

3. Exadata DB管理

3.1 Exadata存储空间计算

FreeMB(最大可用空间) =

GridDisk*12*Num of Cells/Redundancy

UsableMB (支持1个CELL故障的最大可用空间) =

GridDisk*12*(Num of Cells – 1) /Redundancy

3.2 查看cell软件版本

imagehistory

imageinfo

3.3 cell的温度

dcli -g cell_group -l root “ipmitool sensor | grep ‘Inlet Amb Temp‘”

3.4 cell存储节点的日志存放位置

$ADR_BASE/diag/asm/cell/`hostname`/trace/alert.log $ADR_BASE/diag/asm/cell/`hostname`/trace/ms-odl.* $ADR_BASE/diag/asm/cell/`hostname`/trace/svtrc__0.trc — ps -ef | grep “cellsrv 100” $ADR_BASE/diag/asm/cell/`hostname`/incident/*

/var/log/messages*, dmesg /var/log/sa/*

/var/log/cellos/*

3.5 cell中的alert history

list alerthistory where notificationState like ‘[023]’ and severity like ‘[warning|critical]’ and examinedBy = NULL;

3.6 cell创建一个告警阈值

cellcli

create threshold CD_IO_ERRS_MIN warning=1, comparison=’>=’, occurrences=1, observation=1;

3.7 cell可用性监控

一般建议使用 EMGC Oracle Exadata Storage Server Management Plug-In 监控

3.8 禁用Smart Scan

设置 Cell_offload_processing=false

3.9 禁用storage index

设置 _kcfis_storageidx_disabled=true

3.10 禁用flash cache

11.2.0.2 以后 设置_kcfis_keep_in_cellfc_enabled=false

11.2.0.1中设置_kcfis_control1=1

3.11 Cell相关数据库视图

select * from sys.GV_$CELL_STATE;

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;

3.12 配置Inter-Database IORM

CellCLI> alter iormplan –

dbplan = ((name = production, level = 1, allocation = 100), –

(name = test, level = 2, allocation = 80), –

(name = other, level = 2, allocation = 20))

IORMPLAN successfully altered

CellCLI> alter iormplan active

IORMPLAN successfully altered

CellCLI> list iormplan detail

name: cell4_IORMPLAN

catPlan:

dbPlan: name=production,level=1,allocation=100

name=test,level=2,allocation=80

name=other,level=2,allocation=20

status: active

3.13 禁用布隆过滤Bloom Fliter

设置_bloom_pruning_enabled=false

4. Exadata数据备份与恢复

4.1 backup备份速率

Exadata下rman备份的速率从1通道到8通道 大约为1003MB/s 到 2081MB/s，视乎配置不同也略微有区别

4.2 recovery应用日志恢复速率

exadata recovery的速率大约为每秒600~1000MB/s的归档日志

4.3 standby database搭建

对于50TB的standby database搭建，若使用infiniband + 4rman通道大约耗费5.5小时，若使用GigE则在18个小时左右

4.4 Exadata恢复

cell 救护

可以通过

/opt/oracle.SupportTools/make_cellboot_usb脚本创建内部USB cellboot_usb_in_rescure_mode

5. Exadata部署

5.1 onecommand下载

可以下载patch (9935478) ONECOMMAND FOR Exadata 11gR2

5.2 Exadata安装前准备工作

1. 下载安装介质包括Grid, Database,Patches等

2. 硬件设备到货验收并安装就绪

3. 规划DBM用的管理网，生产网，ILOM等用的网段和IP地址

4. 配置DNS服务器

5. 将IP地址和域名注册到DNS服务器

6. 配置NTP服务器

7. 网络连线

5.3 环境检查

1. 检查DBM主机的eth0网卡是否可以通过cisco交换机被访问

2. 检查hardware and firmware profile是否正确

3. 验证InfiniBand Network

5.4 验证网络连通性

1. 登陆第一台数据库服务器使用sh脚本验证网络连通性

2. 验证DNS是否正常

3. 验证NTP 服务器是否正常

5.5 安装Exadata Storage Server Image Patch

备注：(root user)

1. 在db server和cell server上为root用户配置SSH

# /opt/oracle.SupportTools/onecommand/setssh.sh -s -u root -p password -n N -h dbs_group

2. 检查当前Cell storage server的Exadata Image 版本

3. 安装最新的Patch具体步骤详见Readme

4. 验证当前Exadata Image version

#cd /opt/oracle.SupportTools/firstconf

#dcli -l root -g quarter ‘imagehistory | grep –i Version

使用OneCommand工具完成DBM的配置安装

1. #cd /opt/oracle.SupportTools/onecommand

2. Display the onecommand steps

# ./deploy112.sh -i –l

3. The steps in order are…

Step 0 = ValidateThisNodeSetup

Step 1 = SetupSSHForRoot

Step 2 = ValidateAllNodes

Step 3 = UnzipFiles

Step 4 = UpdateEtcHosts

Step 5 = CreateCellipnitora

Step 6 = ValidateHW

Step 7 = ValidateIB

Step 8 = ValidateCell

Step 9 = PingRdsCheck

Step 10 = RunCalibrate

Step 11 = ValidateTimeDate

Step 12 = UpdateConfig

Step 13 = CreateUserAccounts

Step 14 = SetupSSHForUsers

Step 15 = CreateOraHomes

Step 16 = CreateGridDisks

Step 17 = InstallGridSoftware

Step 18 = RunGridRootScripts

Step 19 = Install112DBSoftware

Step 20 = Create112Listener

Step 21 = RunAsmCa

Step 22 = UnlockGIHome

Step 23 = UpdateOPatch

Step 24 = ApplyBP

Step 25 = RelinkRDS

Step 26 = LockUpGI

Step 27 = SetupCellEmailAlerts

Step 28 = RunDbca

Step 29 = SetupEMDbControl

Step 30 = ApplySecurityFixes

Step 31 = ResecureMachine

To run a command

#./deploy112.sh –i –s N

Where N corresponds to a step number

Example to run step 0

6. Exadata监控

6.1 exachk健康检查脚本

exachk脚本可以以daemon形式后台运行

./exachk –d start

以daemon形式cluster support运行

./exachk –clusternodes [node1,[node N]] –d start!

6.2 Exadata文档信息

Exadata的官方文档 http://docs.oracle.com/cd/E50790_01/welcome.html

另外文档还保存在您cell 的 /opt/oracle/cell/doc/ 目录下。