I refer to the article “‘I carried around my piggy bank’: Amid DBS, Citibank service outage, cash is king” (Oct 17).

The recent outage in the provision of bank digital payment services was not the first, and will probably not be the last. The IT infrastructures of financial services firms are interlinked with complicated webs of dependencies and multiple possible points of failure. It is thus vital that there is enough slack in the system such that when one part fails, the system can fail gracefully.

In the fervour to embrace digital innovations, the old paper and tactile-based systems are often ditched in the name of upgrading, a move perhaps also driven by a myopic desire to cut cost, to the detriment of system resilience. 

The systems painstakingly built up over decades to handle and clear cheques are slowly being dismantled. If and when PayNow is not working, the fallback is coins and notes and piggy banks – pity those handling large transactions. Perhaps paying via good old cheques should not be discouraged in good times, so that we have a painless payment alternative in bad times.

Two-factor authentication using physical bank tokens have also been phased out in favour of having the mobile phone act as both the maker and checker of identity, and this coincided with the increase in the number of scams exploiting this security vulnerability. In the final consideration, have the cost savings in phasing out physical tokens taken into account these knock-on costs?

In augmenting system slack and resilience, one example that can be emulated is the migration of parking coupons to a digital app. In extraordinary times, whether it be the app failing due to a deployment error, or the phone being misplaced or stolen or simply out of battery, paper coupons are an excellent fuss-free failsafe. 

Jonathan Khoo (Dr)