VECTOR MQT problem

Problem:

There are values in MATCH_Q_TRAN table but there is no value in BUSY_SCRIPS_TRAN table.

Solution:

Update MatchCopyNo in MATCH_Q_TRAN table for that scrip with the value = 0

Symptom:

There were two values in MATCH_Q_TRAN which were not in BUSY_SCRIP table.

These values were not executing.

Occured after deletion of 57 scrips.It didn't come in MOCK session but occured in live on next day.

Solution:

MatchCopyNo is updated to 9 and ran 9th copy of HMserver manually.

==============================================================================================

1> select * from MATCH_Q_TRAN;

RecId ScripId XactId XactType TradingMode BSFlag

DtTime BPrice BTotalQty

BReplenishQty BPendQty SPrice STotalQty

SReplenishQty SPendQty BrokerCd TraderCd ClientCd OrderDuration

TillDtTime MatchCopyNo LastBTradeId LastSTradeId

TradeSessNo ReferenceCd ShortSellFlag

-------------------- ----------- ----------- -------- ----------- ------

-------------------------- ------------------------ -----------

------------- ----------- ------------------------ -----------

------------- ----------- -------- -------- -------- -------------

-------------------------- ----------- ------------ ------------

----------- -------------- -------------

25888.000000 23004 15960 D H S

Dec 8 2009 1:14PM 0.00 0

0 0 4,320,000.00 200

100 100 SES CTG01 CTG421 GFD

Jan 1 1900 12:00AM 2 0 0

1 NULL N

26798.000000 32009 21378 L H S

Dec 8 2009 1:20PM 0.00 0

0 0 3,722,000.00 500

0 500 SHLCT DHK01 875 GFD

Dec 8 2009 1:20PM 1 0 0

1 NULL N

Failover Technology

A cluster is a group of servers networked together to share the work load. Failover is the process of transferring operation of a failed server to a backup server to ensure websites remain online even due to hardware failure or maintenance. Failover is used to host mission critical websites that require constant availability.

Normal Web server

If a server fails, all sites are down, no mail works, incoming mails circulate in queue.

Failover Server with real-time data replication technology

· A cluster system where one operates web and mail, the other databases. Both get mirrored constantly.

· If server A fails, his work is done by server B

· If server B fails, his work is done by server A

· As soon as both are working again, they get mirrored.

· No offline for website and no late mails.

Database Clustering

Database clustering is the way of achieving higher availability of database.

DB clustering is a failover technology and not scale-out technology. It does not focus on performance or distributing the traffic to different servers. It merely focuses on moving the execution environment and services to another server in a cluster in case of server failure and thus ensures higher availability of database.

Terminologies:

• Cluster: Cluster is a group of computers configured to work together to serve clients in a similar fashion.
• Nodes: Each server participating in a cluster is called as node.
• Max nodes in a cluster: In Windows Server 2003, the maximum number of nodes can be 4 (with at the most 16 SQL instances) whereas in case of Windows NT, maximum number of nodes can be 2 in a cluster.
• Heartbeats: The nodes in a cluster remain in constant communication through the exchange of periodic messages, called heartbeats.
• Same OS on Servers: A cluster cannot be made of nodes running Windows Server 2003 Enterprise Edition and Windows Server 2003 Datacenter Edition. The OS installed on all the nodes must be same.

Virtual IP (VIP): The client system communicates with the DB server using virtual IP. MSCS takes care of redirecting the client request to the active server and hence the client doesn’t have to worry about which server in a cluster is active.