Talk:Elevator algorithm

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I added the merging tags, because these two pages refer to the same thing. Is anyone opposed to making Elevator sort a redirect? --Jamuraa 18:31, 4 March 2006 (UTC)[reply]

Making elevator sort a redirect to this page sounds good to me, they're talking about exactly the same thing. GeorgeBills 12:47, 14 March 2006 (UTC)[reply]

Use of algorithm

Are disk scheduling algorithms actually in use? On which layer are they implemented? Operating system or hard disk? Thanks, --Abdull 19:04, 24 April 2006 (UTC)[reply]

Average Seek Time

When calculating the average seek time for the C-SCAN algorithm, the seek for returning to the begininng of the disk is included, so that the total number of seeks is 6. But the total number of actual disk I/Os is still 5, so should the average be:

185/5 = 37?

Wrong description?

The description says as following:

"As additional requests arrive, requests are serviced only in the current direction of arm movement until the arm reaches the edge of the disk."

But in Andrew S Tanenbaum's "Modern Operating Systems", 5.4.3. it says:

"When a request finishes, the disk or elevator driver checks the bit. If it is UP, the arm or cabin is moved to the next highest pending request. If no requests are pending at higher positions, the direction bit is reversed. When the bit is set to DOWN, the move is to the next lowest requested position, if any."

It seems as though the correct description would be something like:

"As additional requests arrive, requests are serviced only in the current direction of arm movement until the arm reaches the last request, then the arm turns and services the requests in the new direction."

Anyone agree with me?

   -trbox  —Preceding unsigned comment added by Trbox (talk • contribs) 14:59, 2 April 2008 (UTC)[reply]

Hi Trbox. I'd say Tanenbaum is not correct here, or at least he described the algorithm of how a real elevator would be operated - which equals the LOOK algorithm. I base my opinion on this and other lecture notes I've read. I undid your edits. I hope this is fine for you :). Maybe Wikipedia is wrong... maybe it's correct to call LOOK the elevator algorithm. --Abdull (talk) 19:16, 7 August 2008 (UTC)[reply]