# C-LOOK Disk Scheduling Algorithm – Operating System

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C-Look is fairly similar to that of your SCAN algorithms, just a small difference So this is your request queue We have drawn that queue onto the scale in increasing order And we have also mentioned the initial HEAD position (i.e 50) on the scale, here So we begin from here and we traverse towards the left So you go first to 34 then you go to 11 Now we stop because this is the last position towards the left hand side from here we go to the last position on the right hand side which is 180 so we just traverse from 11 to 180 again this head movement will not be considered for calculations while we are calculating the total head movement from 180 we need to go back to the other tracks which we did not access so 123 first then from 123 to 119 from 119 to 95 from 95 to 64 from 64 to 62, that’s it. I have accessed all the tracks in the queue now we need to calculate the total head movement so we will draw the table track accessed No of tracks covered so 50 was the initial position, then we went to 34 No of tracks covered were 16 from 34 we went to 11, no of tracks covered were 23 from 11 we went to 180 but as I said earlier we will not consider it for head movement calculation from 180 we went to 123, so no of tracks covered: 57 from 123 we went to 119, No of tracks : 4 from 119 we went to 95, so no fo tracks: 20 from 95 we went to 64 i.e 31 tracks covered from 64 we went to 62, so no of tracks covered: 2 so this is my end of the table. So what is my total head movement? the total head movement is: 157 What about average seek length? How many tracks did we access? We do not consider the initial position (i.e 50) now although we omitted it from head movement, we did access this (track no 180) right? 8 (total no of tracks accessed) So average seek length: 157/8=19.625

seanslik1Post authorgreat video.. But the last thing you did wasn't fully clear, how you got the seek length?

James BoundPost authordo you have to have to put the scale in numerical order?

Vivek TomerPost authorNonsense video. .before making any video you first need to clear your concept. We have to add 180 in total calculation… becoz that seek is also calculated by system ..

indal PalPost authorits not similar to scan its similar to c-scan………………….its totally wrong we have to add 180 also

Ares - OnePost authordo you know when to start, if they give you current and previous request?

Tasnim OyshiPost authorInitial head point is fixed?? or we can consider anything as our choice?

NAGA SAI GOUD PADAMATIPost authorwhen you are calculating seeking time,why did you left the space for 180 (at time 2:43)

but compared to another videos they didn't left the space,they wrote track covered between 11-180