摘要:
A record media (optical disk) automatic library (back store) houses a plurality of record media for selective mounting in any one of a plurality of media drives (front store). Each record medium has one or more addressable recording surfaces termed data units. Record media currently mounted in said media drives may be replaced by other record media (demounted) only if the individual data unit has been idle (not accessed) for a time longer than a predetermined horizon time (demount eligibility threshold). If the current idle times for all mounted media are less than the respective horizon times, then no media can be demounted. Then, all proposed record media mounts are delayed until one of the currently mounted record media becomes eligible for demounting. If a plurality of mounted record media are eligible for demounting, then a least recently used one of the data units is demounted. The idle time of each mounted data unit is separately timed.
摘要:
A method for managing Data Storage Medium (DSM) mount and demount decisions in an automated data storage library that dynamically optimizes both sequential and random data access workloads. The demount decisions adapt to time-varying characteristics in the relative workload mix. When the workload is primarily sequential, the mount and demount decision procedure favors longer mount residency for sequential access streams, reducing the robotic picker activity and reducing response time for mount requests. When the workload is predominantly random access, sequentially accessed DSM residency time is generally reduced and preemptive demounts are more readily implemented. The disclosed method provides for preemptive demounts and uses a two-element decision process to select either a Least Recently Used (LRU) or a Least Recently Mounted (LRM) decision parameter. The relative weights of the LRU and LRM decision tests are varied responsive to measured changes in data access workload characteristics.
摘要:
Fast formatting of DASD emulating sectors on optical media is provided to reduce initialization time. Rather than format each track media when a new surface of an optical media is mounted in an optical storage library, a table is created on the media containing a set of entries for each track on the media surface. During initialization, a first table entry for each track is set to indicate that the state of the track is reliably KNOWN and a second entry is set to indicate that the track is virgin (unrecorded). Prior to a subsequent data access operation, the track table is copied from the media into a corresponding table in memory and each first entry in the media table is changed to indicate an UNKNOWN state. The memory track table is updated during the data access operations to reflect newly recorded or updated sectors. Upon completion of the data access, the media table is overwritten with the updated memory table.
摘要:
A method to adjust the data transfer rate for one of (N) primary backup appliances. The method forms by a first primary backup appliance at least one consistent transactions set. The first primary backup appliance receives the (n)th status signal, and the (n+1)th status signal from each of the other (N−1) primary backup appliances. The method calculates the (n)th effective bandwidth for each of the (N) primary backup appliances, the (n)th time to complete for each of the (N) primary backup appliances, and the (n)th effective aggregate bandwidth for all (N) primary appliances. If the (n)th time to complete for the first primary backup appliance is greater than the (n)th time to complete for each of the other (N−1) primary backup appliances, then the method provides at least one consistent transactions set from the first primary backup appliance to a first secondary backup appliance with no delay.
摘要:
A method to adjust the data transfer rate for one of (N) primary backup appliances. The method forms by a first primary backup appliance at least one consistent transactions set. The first primary backup appliance receives the (n)th status signal, and the (n+1)th status signal from each of the other (N−1) primary backup appliances. The method calculates the (n)th effective bandwidth for each of the (N) primary backup appliances, the (n)th time to complete for each of the (N) primary backup appliances, and the (n)th effective aggregate bandwidth for all (N) primary appliances. If the (n)th time to complete for the first primary backup appliance is greater than the (n)th time to complete for each of the other (N−1) primary backup appliances, then the method provides at least one consistent transactions set from the first primary backup appliance to a first secondary backup appliance with no delay.
摘要:
A method to write information to an information storage medium. The method creates one or more objects comprising information and provides a first one of those one or more objects. The method writes a header label to an information storage medium, where the header label comprises an object processing indicator. The method assigns a first sequence number to the first object and writes that first object to the information storage medium beginning at a first blockid and ending at a second blockid. The method writes a trailer label to the information storage medium, where that trailer label comprises an embedded object field count. The method writes an object information block to the information storage medium, where that object information block comprises the first sequence number, the first blockid, and the second blockid.
摘要:
Repositioning within an input/output device is accomplished without any knowledge of where the input/output device is currently positioned. The input/output device is repositioned to a predetermined position, in order for a program to be retried. The predetermined position is determined from a previously executed program. The previously executed program is scanned looking for commands. For each command found, a position identifier is adjusted based upon the type of command. When the scan and adjustments are complete, the position identifier represents the predetermined position used for repositioning the input/output device.
摘要:
Repositioning within an input/output device is accomplished without any knowledge of where the input/output device is currently positioned. The input/output device is repositioned to a predetermined position, in order for a program to be retried. The predetermined position is determined from a previously executed program. The previously executed program is scanned looking for commands. For each command found, a position identifier is adjusted based upon the type of command. When the scan and adjustments are complete, the position identifier represents the predetermined position used for repositioning the input/output device.
摘要:
Repositioning within an input/output device is accomplished without any knowledge of where the input/output device is currently positioned. The input/output device is repositioned to a predetermined position, in order for a program to be retried. The predetermined position is determined from a previously executed program. The previously executed program is scanned looking for commands. For each command found, a position identifier is adjusted based upon the type of command. When the scan and adjustments are complete, the position identifier represents the predetermined position used for repositioning the input/output device.
摘要:
An automated data storage library employing a media accessor, an optical disk drive and a removable disk media. The media accessor includes a cartridge shell gripper. The optical disk drive includes a tape cartridge slot. The removable disk media includes a tape cartridge shell having a structural configuration operable to be physically engaged by the cartridge shell gripper and operable to be physically inserted into the tape cartridge slot by the cartridge shell gripper. The removable disk media further includes one or more optical disks disposed within the tape cartridge shell. A recording surface of each optical disk is extractable, partially or entirely, from the tape cartridge shell by the optical disk drive for writing data onto the optical disk and/or reading data from the optical disk.