Question:
How is the User Datagram Protocol (UDP) different than TCP/IP
network protocol?
Is UDP defined for any database being designed or just for Data
warehouse?
What all should be covered in the UDP configuration for an Oracle
system?
Answer:
UDP is stateless, and you DO NOT want to use UDP
for Oracle system where data integrity is an issue. UDP is
available on Linux, AIX, Solaris and HP/UX, and other OS platforms.
Overall, the vast majority of Oracle databases use TCP/IP, because
UDP does not have built-in hand-shake dialogues. This means that
UDP does not have the same data integrity and reliability and
serialization as TCP/IP. With UDP there is no guarantee that your
packet will arrive at the destination and no mechanism for notifying
you of a network failure! Also, UDP is not serialized, so
out-of-order transmission is possible.
So, why choose UDP? If you are on a super-reliable network where
you have zero lost packets possibilities then you may choose UDP
because it is far faster than TCP/IP, primarily because there is no
overhead in establishing a handshake connection. UDP is stateless.
UDP Parameters for AIX
However, UDP is far faster than TCP/IP, so the UDP protocol is used
for high impact communications areas such as domain name servers
(DNS) UDP for AIX:
In AIX, you can adjust the UDP kernel settings with the network
options (?no?) command, which can alter the udp_sendspace
and udp_recvspace parameters. To enable UDP on AIX for
Oracle, you set the following UDP parameters:
-
udp_sendspace: Set udp_sendspace
parameter to [(DB_BLOCK_SIZE *DB_FILE_MULTIBLOCK_READ_COUNT) +
4096], but not less than 65536.
-
udp_recvspace: Set the value of the
udp_recvspace parameter to be >= 4 * udp_sendpace.
The value of the udp_recvspace parameter should be at
least four to ten times the value of the udp_sendspace
parameter because UDP might not be able to send a packet to an
application before another packet arrives. To determine the
suitability of the udp_recvspace parameter settings,
enter the following command:
netstat -s | grep 'socket buffer overflows?
-
sb_max: If required, set the
sb_max parameter (default value is 1048576) to a higher
value because sb_max must be greater than
udp_recvspace
UDP Parameters for Solaris
To enable UDP in Solaris for Oracle, initialize the following UDP
kernel parameters:
-
udp_xmit_hiwait: The
udp_xmit_hiwait parameter defines the default maximum UDP
socket datagram size and is related to udp_max_buf.
-
udp_recv_hiwait: The udp_recv_hiwait
parameter specifies the default maximum UDP socket receive
buffer size.
-
udp_max_buf: The udp_max_buf
parameter determines the size of the OS send and receive buffers
for a UPD socket.
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