Major Mohammad Roasri Erwan bin Haji Tasrif was born on 08 December 1978 in Berakas Camp. He joined the Royal Brunei Armed Forces on 16 January 1994 when he enlisted and began basic military training and academic studies in Intake 16, Boys Company, Training Centre RBAF. Major Mohammad Roasri Erwan graduated with a Bachelor of Engineering (Honours) in Electronics System Design from Bournemouth University, United Kingdom in 2001 and was awarded the Master of International Security from Massey University, New Zealand in 2016.
After completion of the Officer Cadet Course in Singapore in the year 2002, Major Mohammad Roasri Erwan was commissioned as a Lieutenant and appointed as the Platoon Commander of 'A' Company 2Bn RBLF. From the year 2006 until 2009, Major Mohammad Roasri Erwan has held various appointments at the Bolkiah Workshop of Land Engineering RBLF (then known as Land Engineering Support Service RBAF). Among the appointments were OIC Optronics, OIC Mechanical and OIC Production. On 01 February 2009, he was appointed as the Aide-De-Camp to Deputy Minister of Defence and subsequently, held the appointment of Acting Officer Commanding of 'D' Company 1Bn RBLF. In 2011, he returned to Land Engineering and was appointed as the Officer Commanding of Bolkiah Workshop, RBLF. In 2015, he was appointed as the Staff Officer 2 to Commander of the Royal Brunei Armed Forces and in 2017, as the Second-In-Command (2IC) of 3Bn RBLF. Major Mohammad Roasri Erwan bin Haji Tasrif assumed the appointment as the Commanding Officer 1Bn RBLF on 23 July 2018.
In 2012 to 2013, he was given the opportunity and honour as the head of RBAF Contingent to conduct peacekeeping mission as part of United Nations Interim Forces in Lebanon (UNIFIL) under the Malaysian Company 8 (MALCOY 8).
Throughout his service, Major Mohammad Roasri Erwan attended various local and abroad courses which includes Platoon Commander Course (TI RBAF), Company Commander Tactics Course (PULADA, Malaysia), Battalion Tactics Course (SAFTI MI, Singapore) and the 5th RBAF Command and Staff Course.
Major Mohammad Roasri Erwan is a member of Institution of Engineering and Technology (MIET), United Kingdom and for his commitment to RBAF Engineering Excellence and professional competence, he was awarded Incorporated Engineer (IEng) from the Engineering Council United Kingdom in 2015.
In recognition of his service, Major Mohammad Roasri Erwan was awarded The Most Blessed Order of Setia Negara Brunei 4th Class (Darjah Setia Negara Brunei Yang Amat Bahagia Darjah Keempat, PSB) in 2012 and the Meritorious Service Medal (Pingat Jasa Kebaktian, PJK) recently in 2013 by His Majesty the Sultan and Yang Di-Pertuan of Brunei Darussalam.