New Delhi, Mar 22 (PTI) The National Stock Exchange (NSE) on Monday said failure of telecom links as well as that of storage area network system led to the outage at the bourse last month.
In a detailed statement, the bourse said various measures have been taken and others are under implementation to address the issues.
Between primary and NDR (Near Disaster Recovery) sites, NSE said it has multiple telecom links with two service providers to ensure redundancy.
'On February 24, 2021 we had instability in links from both service providers primarily due to digging and construction activity along the path between the two sites,' the exchange said.
On that day, post link failure, the exchange said it saw unexpected behaviour of the Storage Area Network (SAN) system, with the primary SAN becoming inaccessible to the host servers. This resulted in the risk management system of NSE Clearing and other systems such as clearing and settlement, index and surveillance systems becoming unavailable.
'While there was no impact on the trading system, given that the risk management system was unavailable, allowing trading to continue on NSE posed an unacceptable risk, and hence trading had to be halted,' the exchange said.
The SAN is a fault tolerant system that was designed to function seamlessly even in the event of telecom link failures between primary and NDR copies.
One of the features of SAN that was deployed in October 2020 was designed to provide not just zero data loss but also zero down time. Before deployment, the system was tested against various scenarios including link failures and functioned properly, as per NSE.
Further, the bourse said various steps have already been taken and others are under implementation to address the SAN and telecom link issues.
Trading activity at NSE halted for nearly for hours on February 24. PTI SP RAM RAM