Logging latency reduction
A disk is divided into K angular regions. A log write request is replicated K times and K number of identical log writes are issued to the disk to be written to each of the angular regions of the log. Upon completion of the first write, the application requesting the log write is informed of its completion resulting in a reduction of rotational latency by a factor of K.
1. A method for decreasing rotational latency associated with a log write issued by an application to a rotating medium using a data writing element, the method comprising:
dividing a track on the rotating medium into a plurality of discrete angular regions;
replicating said log write to form a plurality of identical disk writes equal in number to the plurality of discrete angular regions;
writing the plurality of identical disk writes to the plurality of discrete angular regions of the track such that each one of the plurality of discrete angular regions comprises one of the plurality of identical disk writes; and
responsive to completion of a first disk write of the plurality of identical disk writes to one of the plurality of discrete angular regions of the track, informing said application of completion of the log write,
wherein upon completing a second disk write of the plurality of identical disk writes, the method further comprises ignoring thereafter the second disk write of the plurality of identical disk writes, wherein said application is not informed of the completing of the second disk write of the plurality of identical disk writes, wherein the application is idle during the first disk write and is not idle during the second disk write and the application can continue to operate.
2. The method of claim 1 wherein said plurality of discrete angular regions are uniformly distributed throughout the track.
3. The method of claim 1 wherein each log write issued by said application includes unique identification information linking said log write to said application.
4. The method of claim 1 wherein said plurality of discrete angular regions are distributed among a plurality of tracks on a plurality of rotating mediums.
5. The method of claim 1 further comprising:
monitoring the data writing element location with respect to the plurality of discrete angular regions of the track, wherein said informing step comprises communicating information as to which of the plurality of discrete angular regions said first disk write was written to, wherein said monitoring comprises utilizing said information;
replicating a next in time log write to form a next plurality of identical disk writes equal in number to the plurality of discrete angular regions; and
limiting, based on said information, the writing of the next in time log write to the discrete angular region of the track immediately ahead of the discrete angular region said first disk write was written to.
6. A method for decreasing rotational latency associated with a plurality of log write requests issued by a plurality of applications to a rotating medium using a data writing element, the method comprising:
dividing a track on the rotating medium into K discrete angular regions, wherein K is an integer greater than or equal to the number 2 such that K squared is less than or equal to a maximum number of requests said rotational medium can concurrently conduct:
combining, into a disk write, the plurality of log write requests, wherein the combining occurs over a first period of time, wherein the first period of time is equal to a multiplicative inverse of K multiplied by a period of time of one rotation of the rotating medium;
replicating said disk write to form K identical disk writes;
writing the K identical disk writes to the K discrete angular regions on the track of the rotating medium; and
communicating to the plurality of applications a completion of a first disk write of the K identical disk writes to one of the K discrete angular regions of the track, wherein each of the plurality of log write requests issued by each of said plurality of applications includes unique identification information linking each of the plurality of log write requests to at least one of the plurality of applications wherein upon completing a second disk write of the K identical disk writes, the method further comprises ignoring thereafter the second disk write of the K identical disk writes, wherein said plurality of applications are not informed of the completing of the second disk write of the K identical disk writes, wherein the applications are idle during the first disk write and are not idle during the second disk write and the applications can continue to operate.
7. The method of claim 6 wherein said K discrete angular regions are uniformly distributed throughout the track.
8. The method of claim 6 wherein said K discrete angular regions are distributed among a plurality of tracks on a plurality of rotating mediums.
9. The method of claim 1 , wherein said informing said application of completion of the log write occurs during said writing said plurality of identical disk writes to said plurality of discrete angular regions.
10. The method of claim 1 , further comprising limiting the writing of a next in time log write to a discrete angular region of the track immediately ahead of the discrete angular region to which the first disk write was written to.
11. The method of claim 1 , wherein said application is not informed of the completing of the writing of the plurality of identical disk writes.