在数据库方面，NFS也能得以应用。今天我们主要讲解的就是Oracle Direct NFS方面的内容。文中我们详尽讲解了其中的测试过程，以及配置的具体方法，希望对大家有所帮助。那么，测试了一下Oracle Direct NFS的功能，发现ORACLE Direct NFS是通过建立多个到NFS Server的TCP连接来提高IO的并发能力的。前面，我们提过，NFS的IO能力不高的原因是，NFS client端到NFS Server的操作是串行的，正常的NFS client到NFS Server端只建立一个连接，而且只有等前一个请求处理完成后，后一个请求才能处理，这样在随机读IO上就上不去。而Oracle Directd NFS与NFS Server建立多个TCP连接，处理就可以并发进行了，这样从理论上说就可以大大提高NFS的性能。
而在实际发现Direct NFS读的时候很快，实测到达到了400Mbytes/s，基本没有发现瓶颈，但写的时候，发现比较慢，insert数据时，写流量只有3.4Mbytes/s左右，写为何这么慢原因不明，估计是Linux的NFS Server与Oracle Direct NFS配合不好导致。当使用rman备份时，如果备份的路径在Direct NFS指定的路径中时，也会自动走到Direct NFS模式下。
测试过程：
先修改odm库，启动支持Direct nfs的odm库：
[oracle@nfs_client lib]$ ls -l *odm*
-rw-r–r– 1 oracle oinstall 54764 Sep 11 2008 libnfsodm11.so
lrwxrwxrwx 1 oracle oinstall 12 Jul 8 18:55 libodm11.so -> libodmd11.so
-rw-r–r– 1 oracle oinstall 12755 Sep 11 2008 libodmd11.so
[oracle@nfs_client lib]$ rm libodm11.so
[oracle@nfs_client lib]$ ln -s libnfsodm11.so libodm11.so
在nfs server机器中共享一个目录，为了使用硬盘不会成为IO瓶颈，使用8块盘做一个raid0，然后做ext3文件系统，做为nfs Server的输出：
mdadm -C /dev/md0 –level raid0 -c 8 -n 8 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh /dev/sdi
mkfs -t ext3 /dev/md0
mount /dev/md0 /nfs
然后在/etc/exportfs中配置：
/nfs 192.168.172.132(rw,no_root_squash,insecure)
service nfs restart
在数据库主机上(nfs client端）：
[oracle@nfs_client dbs]$ cat oranfstab
server: node_data1
path: 192.168.172.128
export: /nfs mount: /opt/oracle/oradata/nfsmount -t nfs 192.168.172.128:/nfs /opt/oracle/oradata/nfs
两台机器通过万兆网卡连接，测试过网络速度可以达到800Mbytes/s以上。#p#
建一个数据库：
CREATE DATABASE oratest
USER SYS IDENTIFIED BY sys
USER SYSTEM IDENTIFIED BY system
CONTROLFILE REUSE
LOGFILE GROUP 1 (’/opt/oracle/oradata/oratest/redo_1_1.log’) SIZE 200M REUSE,
GROUP 2 (’/opt/oracle/oradata/oratest/redo_2_1.log’) SIZE 200M REUSE,
GROUP 3 (’/opt/oracle/oradata/oratest/redo_3_1.log’) SIZE 200M REUSE,
GROUP 4 (’/opt/oracle/oradata/oratest/redo_4_1.log’) SIZE 200M REUSE,
GROUP 5 (’/opt/oracle/oradata/oratest/redo_5_1.log’) SIZE 200M REUSE
MAXLOGFILES 20
MAXLOGMEMBERS 5
MAXLOGHISTORY 1000
MAXDATAFILES 1000
MAXINSTANCES 2
noARCHIVELOG
CHARACTER SET US7ASCII
NATIONAL CHARACTER SET AL16UTF16
DATAFILE ‘/opt/oracle/oradata/oratest/system01.dbf’ SIZE 2046M REUSE
SYSAUX DATAFILE ‘/opt/oracle/oradata/oratest/sysaux01.dbf’ SIZE 2046M REUSE
EXTENT MANAGEMENT LOCAL
DEFAULT TEMPORARY TABLESPACE temp
TEMPFILE ‘/opt/oracle/oradata/oratest/temp01.dbf’ SIZE 2046M REUSE
UNDO TABLESPACE undotbs1
DATAFILE ‘/opt/oracle/oradata/oratest/undotbs01.dbf’ SIZE 2046M REUSE
SET TIME_ZONE = ‘+08:00′;
再建一个表空间tbs_testd在在nfs上：
create tablespace tbs_test datafile ‘/opt/oracle/oradata/nfs/test01.dbf’ size 2047M;
SQL> col svrname format a40
SQL> col dirname format a40
SQL> set linesize 200
SQL> select * from v$dnfs_servers;ID SVRNAME DIRNAME MNTPORT NFSPORT WTMAX RTMAX
———- —————————————- —————————————- ———- ———- ———- ———-
1 nfs_server /nfs 907 2049 32768 327681 row selected.
col filename format a40
select * from v$dnfs_files;SQL> select * from v$dnfs_files;
FILENAME FILESIZE PNUM SVR_ID
—————————————- ———- ———- ———-
/opt/oracle/oradata/nfs/test01.dbf 2145394688 9 1SQL> col path format a30
SQL> select * from V$DNFS_CHANNELS;
#p#
PNUM SVRNAME PATH CH_ID SVR_ID SENDS RECVS PINGS
———- —————————————- —————————— ———- ———- ———- ———- ———-
5 nfs_server 192.168.172.128 0 1 9 25 0
9 nfs_server 192.168.172.128 0 1 28 75 0
11 nfs_server 192.168.172.128 0 1 96 250 0
12 nfs_server 192.168.172.128 0 1 166 552 0
13 nfs_server 192.168.172.128 0 1 216 955 0
14 nfs_server 192.168.172.128 0 1 3 7 0
15 nfs_server 192.168.172.128 0 1 351 1057 0
17 nfs_server 192.168.172.128 0 1 899 2708 0
18 nfs_server 192.168.172.128 0 1 3 7 0
19 nfs_server 192.168.172.128 0 1 2 4 0
20 nfs_server 192.168.172.128 0 1 10 30 0
21 nfs_server 192.168.172.128 0 1 37 109 0
22 nfs_server 192.168.172.128 0 1 18 52 0
13 rows selected.
在Oracle Direct NFS server上查看到2049端口的连接：
[root@nfs_server data]# netstat -an |grep 2049
tcp 0 0 0.0.0.0:2049 0.0.0.0:* LISTEN
tcp 0 0 192.168.172.128:2049 192.168.172.132:14111 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:51478 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:61228 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:52532 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:10827 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:31047 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:55132 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:866 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:32634 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:54646 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:47987 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:22448 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:49091 ESTABLISHED
执行：insert into test select * from test;时使用自已写的查看网卡流量的脚本iftop查看网络流量中,可以写流量只有3.4Mbytes/s#p#
ifname in_kbytes/s out_kbytes/s all_kbytes/s in_packets/s out_packets/s all_packets/s
——— ———– ———— ———— ———— ————- ————-
eth2 3133 99 3232 2370 770 3140
eth2 3364 147 3511 2559 837 3396
eth2 3630 1511 5142 2828 1845 4673
eth2 3315 103 3419 2517 785 3302
eth2 3380 105 3486 2535 796 3331
eth2 3627 113 3741 2718 854 3572
eth2 3610 112 3722 2704 853 3557
eth2 3586 113 3700 2713 862 3575
eth2 3471 107 3579 2589 804 3393
eth2 3470 108 3578 2618 822 3440
eth2 3347 105 3453 2525 807 3332
eth2 3406 106 3512 2549 809 3358
eth2 3351 106 3458 2547 814 3361
eth2 3248 101 3349 2427 769 3196
eth2 2743 87 2831 2080 666 2746
而执行select count(*) from test;时可以看到网络流量很高，高的时候达到400Mbytes/s.在NFS Server端查看连接到2049端口的连接数，可以看到有很多个连接，这与使用操作系统的NFS client端是不一样的，使用操作系统的NFS client端，到服务器的连接只有一个，由此可见，Oracle Direct NFS通过与服务器建立多个TCP连接来实现高并发IO，从而提升NFS的性能。连接的数目的多少与压力的大小有关，压力越大，连接数越多。
[root@nfs_server nfs]# netstat -an |grep 2049
tcp 0 0 0.0.0.0:2049 0.0.0.0:* LISTEN
tcp 166768 0 192.168.172.128:2049 192.168.172.132:20048 ESTABLISHED
tcp 173716 140 192.168.172.128:2049 192.168.172.132:22625 ESTABLISHED
tcp 172772 0 192.168.172.128:2049 192.168.172.132:28796 ESTABLISHED
tcp 170832 0 192.168.172.128:2049 192.168.172.132:4468 ESTABLISHED
tcp 171764 140 192.168.172.128:2049 192.168.172.132:42147 ESTABLISHED
tcp 172684 0 192.168.172.128:2049 192.168.172.132:63693 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:48835 ESTABLISHED
tcp 170500 0 192.168.172.128:2049 192.168.172.132:57326 ESTABLISHED
tcp 171772 0 192.168.172.128:2049 192.168.172.132:43246 ESTABLISHED
tcp 0 0 192.168.172.128:2049 192.168.172.132:36080 ESTABLISHED
udp 0 0 0.0.0.0:2049 0.0.0.0:*
