0 votes 0 votes A disk has $200$ tracks (numbered $0$ through $199$). At a given time, it was servicing the request of reading data from track $120$, and at the previous request, service was for track $90$. The pending requests (in order of their arrival) are for track numbers. $30\:70\:115\:130\:110\:80\:20\:25$ How many times will the head change its direction for the disk scheduling policies SSTF(Shortest Seek Time First) and FCFS (First Come First Serve)? $2$ and $3$ $3$ and $3$ $3$ and $4$ $4$ and $4$ Operating System nielit2017july-scientistb-cs operating-system disk-scheduling + – admin asked Mar 30, 2020 retagged Oct 27, 2020 by Krithiga2101 admin 861 views answer comment Share Follow See 1 comment See all 1 1 comment reply smsubham commented Apr 3, 2020 reply Follow Share Previous year https://gateoverflow.in/3705/gate2004-it-62 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes Option C is correct. Observation : R/W head is moving outside (90 to 120) initially. For SSTF direction changes at following tracks : 120, 100 and 130. For FCFS direction changes at following tracks : 120, 30, 130 and 20 . Pat_007 answered Aug 17, 2020 Pat_007 comment Share Follow See 1 comment See all 1 1 comment reply habedo007 commented Oct 8, 2020 reply Follow Share There is no service for track 100. You should correct it to track 80 in SSTF. 0 votes 0 votes Please log in or register to add a comment.