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AIX 환경의 인포믹스 서버로 클라이언트 접속 지연 현상에 대해서 테스트해보았습니다.

 

먼저 AIX서버의 /etc/resolv.conf 파일의 내용은 아래와 같이 설정했습니다. (SK브로드밴드 DNS입니다)

nameserver 210.220.163.82

 

그리고 네임서비스를 위해 설정하는 /etc/netsvc.conf 파일의 내용은 기본적으로 주석만 있었으며

명시적으로 아래와 같이 순서를 지정할 수 있습니다.

hosts = local , bind

 

여기서 local은 /etc/hosts 파일을, bind는 DNS 서버를 참조하도록 합니다.

 

테스트를 위해 /etc/netsvc.conf 파일 내용을 수정해서 DB 접속시 오픈하는 파일을 확인해 보았습니다.

 

## /etc/netsvc.conf, hosts = bind

$ truss -d -o outfile_bind dbaccess sysmaster -e
$ cat outfile_bind | grep open

....

0.4493:        kopen("/etc/resolv.conf", O_RDONLY) = 6
0.4510:        kopen("/etc/netsvc.conf", O_RDONLY) = 6
0.4523:        kopen("/etc/hesiod.conf", O_RDONLY) Err#2  ENOENT
0.4525:        kopen("/etc/irs.conf", O_RDONLY) Err#2  ENOENT
150.5290:        kopen("/work2/INFORMIX/1150FC9/msg/itoxmsg.pam", O_RDONLY) = 6
150.5497:        kopen("/work2/INFORMIX/1150FC9/msg/en_us/0333/sql.iem", O_RDONLY) = 3

 

## /etc/netsvc.conf, hosts = local

$ truss -d -o outfile_local dbaccess sysmaster -e
$ cat outfile_bind | grep open

....

0.4696:        kopen("/etc/resolv.conf", O_RDONLY) = 6
0.4716:        kopen("/etc/netsvc.conf", O_RDONLY) = 6
0.4733:        kopen("/etc/irs.conf", O_RDONLY) Err#2  ENOENT
0.4779:        kopen("/etc/hosts", O_RDONLY)    = 6
0.4794:        kopen("/etc/hosts", O_RDONLY)    = 6
0.4970:        kopen("/work2/INFORMIX/1150FC9/msg/en_us/0333/sql.iem", O_RDONLY) = 3

 

/etc/netsvc.conf 파일의 hosts를

bind로 설정했을 때는 /etc/resolv.conf /etc/netsvc.conf, /etc/hesiod.conf, /etc/irs.conf 파일들을 참조하고,

local로 설정하면 /etc/resolv.conf 및 /etc/hosts 파일을 참조하는 것을 확인할 수 있습니다.

 

 

http://www-01.ibm.com/support/knowledgecenter/ssw_aix_71/com.ibm.aix.files/netsvc.conf.htm

http://informix-technology.blogspot.kr/2012/01/dns-impact-on-informix-impacto-do-dns.htmlhttp://www-01.ibm.com/support/docview.wss?uid=swg21661279
https://www.ibm.com/developerworks/community/blogs/idsteam/entry/why_dbaccess_always_query_dns_server_while_connecting_to_a_database?lang=en

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Slow connect time to Informix when using TCP/IP  (0) 2011.12.20
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Problem(Abstract)

Client applications using the TCP/IP protocol to connect to Informix experience poor performance during connection. once the connection has been established the performance is improved.

Cause

  • During connection establishment, the IP address of the client is used by the IDS server to look up its host name. The method used to accomplish this is dependent on the configuration of the operating system. If the Domain Name System (DNS) is used, an operation known as a reverse query is used to map the IP address to host name. If the configuration of the DNS server is incomplete this type of query may take some time.

    The command line utility nslookup may be used to perform DNS queries. If a reverse lookup operation takes a long time to complete using nslookup then the IDS server will also take a long time to complete the same operation.

    The first example shows a reverse lookup operation for an IP address that is known to the DNS server and completes immediately. The second example uses an IP address that is unknown taking several seconds before returning an error.

    C:\>nslookup 1.2.3.4
    Server:  host1.domain.com
    Address:  9.8.7.6

    Name:    host222.domain.com
    Address:  1.2.3.4

    C:\>nslookup 9.69.1.126
    Server:  host1.domain.com
    Address:  9.8.7.6

    DNS request timed out.
    timeout was 2 seconds.
    *** Request to host1.domain.com timed-out
  • The lookup for the service name could be taking a while.
  • Another cause may by the use of IPv6 addresses with DNS servers that are not configured for IPv6.

Diagnosing the problem

To isolate the problem to tcp/ip connections try to connect by way of a shared memory connection. If the connection is now completed quickly then the problem outlined above may be the cause of poor connection performance.

Follow this link if you need instructions for setting up shared memory connections:
A shared-memory connection (UNIX)


Resolving the problem

  • Refer to your operating system documentation for details of how to configure DNS. If the DNS server runs on the Microsoft Windows® platform then it is possible that the zone used to implement reverse lookup is not implemented. Details regarding DNS on the Windows operating system can be found in the related URLs below. Ensure that the reverse-lookup zone is populated for all clients that connect to the IDS server.
  • Ensure that local hostname resolution is performed before other methods of hostname resolution (NIS, NIS+, DNS, and so on). Files like these are used on various operating systems to determine lookup order:

    /etc/netsrv.conf
    /etc/irs.conf
    /etc/nsswitch.conf
  • Reconfigure your operating system to not use DNS, for example by including the host names and IP addresses of all client machines in the local hosts file /etc/hosts or %WINDIR%\system32\drivers\etc\hosts on Windows.
  • Change the host name in the sqlhosts file to an IP address.
  • Change the service name in the sqlhosts file to the port number.
  • Connections to IDS hang


https://www-304.ibm.com/support/docview.wss?uid=swg21250028

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