Method and apparatus for reinitializing a tape drive after a power loss

A method and apparatus to quickly and correctly re-initialize a tape drive mechanism after power loss employs a non-volatile memory to store functional state data during normal operation of the tape drive mechanism. After a power loss, the functional state data is read from the non-volatile memory so that the tape drive mechanism can be properly re-initialized based on the recovered functional state data.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for quickly and consistently reinitializing a tape drive after a loss of power to the tape drive.

DESCRIPTION OF RELATED ART

Single reel tape cartridges are used to transport and store tape for reel-to-reel tape drives. A single reel tape cartridge is inserted into a tape drive and a mechanism is used to load the end of the tape into a take-up reel from the tape cartridge. Once the end of the tape is loaded into the take-up reel, the tape drive operates as a reel-to-reel tape drive. A motor is coupled to the take-up reel to rotate the take-up reel about the take-up reel axis and another motor is coupled to the single reel tape cartridge to rotate the reel of the tape cartridge about its axis.

The tape drive mechanism attaches to a tape leader pin, located at the end of the tape contained in the single reel tape cartridge. The hub filler uses a slot in the hub filler for receiving the tape leader pin. The hub filler is coupled to a guide arm that drives the hub filler between the single reel tape cartridge and the take-up reel. An example of a mechanism for driving the hub filler between the tape cartridge and the take-up reel is disclosed in U.S. Pat. No. 6,034,839.

FIG. 1is a view of the tape drive mechanism disclosed in U.S. Pat. No. 6,034,839. The hub filler300enters into the cartridge210and attaches to the end of the tape. The hub filler300then moves along a guide rail247, driven by the guide arm250. Typically, the hub filler300attaches to the end of a tape in the tape cartridge210and the guide arm250moves the hub filler300along the guide rail247, trailing the tape across the read/write head222and into the take-up reel242. The hub filler300enters the take-up reel242through a channel244and into the hub245of the take-up reel242.

FIG. 2is a top view of the tape drive mechanism, depicting the hub filler300in the take-up reel242with the tape216attached. The single reel tape cartridge210is positioned in the tape drive. The tape216is wound on a reel inside the cartridge210. The end of the tape216is attached to a leader pin214. The hub filler300has transported the end of the tape216along the guide rail247, driven by the guide arm250, from the cartridge210to the take-up reel242. During this transportation hub filler300pivots on axle252and is held to the guide rail247by pressure from a spring. The hub filler300also includes a catcher that attaches to the leader pin214when entering the cartridge210. The tape216is passed across the read/write head222and the end of the tape216is secured to the take-up reel242. The tape drive is then operated by rotation of the take-up reel242and the single reel of the cartridge210about their respective axes to move the tape216across the read/write head222. Motors are used to rotate the take-up reel242and the single reel of the cartridge210, controlling the speed of the tape216as it moves across the read/write head222. The hub filler300pivots on an axle252that is coupled to the guide arm250. This pivoting is necessary for the hub filler300to be guided on the guide rail247into the take-up reel242. Once the hub filler300is in the take-up reel242, with the tape216attached, the take-up reel242rotates to thereby unload the tape from the cartridge210. The hub filler300rotates with the take-up reel242on the axle252.

There are some concerns regarding the conventional tape drive described above. During the sequence of operations of a conventional tape drive mechanism there is a possibility of a power loss. When power is eventually restored to the tape drive, it is difficult for a controller that controls the mechanical operation of the conventional tape drive to determine what operation in the sequence of operations the conventional tape drive was performing at the time of power loss. In other words, the controller does not know, after the restoration of power, how to continue operation of the tape drive. When the conventional tape drive inevitably continues operation after restoration of power, there is a likelihood that the leader pin214will become disengaged from the hub filler300. This problem may exist when, at the time of power loss, the hub filler300was in between the tape cartridge210and take-up reel242. Such a circumstance will effectuate a “jam” in a tape drive and cause the tape drive to be temporarily inoperable. This circumstance is very inconvenient for the user of the “jammed” tape drive and may cause significant delays for the user.

Some conventional tape drives include sensors that sense the position of the mechanical parts of the tape drive mechanism after recovery of power. However, these sensing arrangements can be somewhat inaccurate and this inaccuracy can cause the tape drive mechanism to be “jammed”, as discussed above. Further, this sensing of the position of the mechanical parts after a power recovery often does not provide enough information to determine the direction the mechanical parts were moving when the power loss occurred. In other words, the conventional tape drive mechanism cannot consistently resume operation during reinitialization from where the tape drive mechanism was operating prior to power loss. This may cause an undesirable delay during reinitialization. Further, the hardware necessary for sensing the position of mechanical parts of the conventional tape drive takes up valuable space in the tape drive, which is undesirable in compact tape drives.

SUMMARY OF THE INVENTION

There is a need for a tape drive that can consistently resume operation during reinitialization after a power loss, with minimum time delay. There is also a need for a tape drive mechanism that can consistently resume operation during reinitialization after a power loss, but consumes minimal space.

These and other needs are met by embodiments of the present invention, which provide a method and apparatus of utilizing a non-volatile memory that stores the functional state of a tape drive throughout the operation thereof. Particularly, in embodiments of the present invention, the tape drive mechanism is arranged to store in the non-violatile memory the last instruction issued from a controller to the tape drive mechanism. This last issued instruction is further stored in relation to the sequence of instructions that the tape drive mechanism is performing at time of storage. Accordingly, if a power loss occurs during the operation of the tape drive mechanism according to an issued instruction, the tape drive is arranged to read the functional state of the tape drive mechanism from the non-volatile memory during reinitialization.

The present invention has the advantage of fast reinitializing after power loss. This is possible, since the last issued instruction in relation to the sequence of instructions that the tape drive mechanism was performing at the time of power loss is stored in the non-volatile memory. Accordingly, after a power loss, the tape drive mechanism can resume operation without significant delay during reinitialization. Hence, it is unnecessary for the tape drive to sense or attempt to determine where in the sequence of instructions the tape drive was at the time of power loss, based on the position of the mechanical parts of the tape drive mechanism.

Another advantage of the present invention over a conventional tape drive is that mechanical failure or “jamming” is less likely to occur. In embodiments of the present invention, the tape drive can resume operation at the same instruction in the sequence of instructions during reinitialization with a significant reduction, in comparison to a conventional tape drive, in the probability of mechanical failure or “jamming”. For instance, in a conventional tape drive, if a hub filler is transporting an end of tape with a leader pin attached, it is possible for the leader pin to detach from the hub filler during reinitialization. This causes the tape to be “jammed” in the tape drive. This can occur for a variety of reasons. One reason is that during reinitialization of a conventional tape drive, it is necessary to perform several mechanical operations to sense the position of the hub filler. Accordingly, during these mechanical operations, the leader pin can be inadvertently detached from the hub filler. Another reason is that during reinitialization, it may not be possible through the use of sensors to determine where in the sequence of instruction the conventional tape drive mechanism was operating during the power loss. More particularly, the conventional tape drive mechanism may not be able to determine whether the tape was being loaded or unloaded at time of power loss. Accordingly, the tape drive of the present invention alleviates this disadvantage by storing the functional state in relation to the sequence of instruction the tape drive mechanism was performing at time of power loss, so that during reinitialization the tape drive mechanism can efficiently and consistently resume operation.

The foregoing and other features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the present invention, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method and apparatus, utilizing a non-volatile memory for storing the functional state of a tape drive mechanism. The tape drive mechanism is arranged to load and unload tape from a single reel tape cartridge. These loading and unloading operations require a sequence of instructions from a controller of a tape drive. After each issuance of an instruction in a sequence of instructions from the controller, the functional state or the last instruction issued from the controller is stored in the non-volatile memory. Accordingly, during reinitialization of the tape drive mechanism after a power loss, the functional state is read from the non-volatile memory and utilized to efficiently and consistently continue the sequence of instructions the tape drive mechanism was performing at the time of power loss. This reading of the functional state during reinitialization can prevent the detachment of a hub filler from a leader pin, for example. Further, this reading of the functional state during reinitialization prevents the repeating of an operation the tape drive had already performed prior to the power loss.

FIG. 3is a block diagram depicting an exemplary relationship between a tape drive mechanism, a controller, and a non-volatile memory. Controller704controls the mechanical operation of tape drive mechanism702. In order for the tape drive mechanism702to perform the operations necessary for the operation of the tape drive mechanism702, instructions from the controller704must be received. For instance, the tape drive mechanism702may be attaching to the end of a tape in a tape cartridge. For such an operation, the controller704sends instructions to the tape drive mechanism702. As an example, these instructions specifically instruct the mechanical components of the tape drive mechanism702to insert a hub filler of the tape drive mechanism702into a tape cartridge and attach the hub filler to a leader pin. After the attachment, the tape drive mechanism702receives further instructions which specifically control the movement of the hub filler with the attached leader pin to a take-up reel. These instructions may include the direction of movement of a component, the speed of such a movement, and the timing of such a movement. One of ordinary skill in the art will appreciate other instructions necessary to control the operation of a tape drive mechanism702, which controller704can provide.

Instructions provided by controller704to the tape drive mechanism702are often complex and involved. Accordingly, these instructions may be in the form of a sequence of instructions. A non-volatile memory706is coupled to the controller704. In embodiments of the present invention, the controller704stores an instruction and/or the functional state in the non-volatile memory706, after the controller704has issued an instruction to the tape drive mechanism702. The instruction sent to the tape drive mechanism702from the controller704directly relates to the functional state of the tape drive mechanism702. Accordingly, when the controller704stores an instruction in relation to the sequence of instructions sent to the tape drive mechanism, the controller704is effectively storing the functional state of the tape drive mechanism702in the non-volatile memory706.

Non-volatile memory706is an example of non-volatile data storage. There are multiple embodiments that can comprise such non-volatile data storage. In some embodiments the non-volatile data storage is an electrically erasable programmable read only memory (EEPROM). An EEPROM is a reprogrammable read-only memory in which memory cells may be erased electrically and in which each memory cell may be reprogrammed electrically. An EEPROM can only be erased and reprogrammed by electronic methods. In other embodiments, the non-volatile data storage may be a bubble memory. A bubble memory is a type of non-volatile storage that uses magnetic fields to create regions of magnetization. In a bubble memory, a pulsed field breaks the regions of magnetization into isolated bubbles; the pulse field is free to move along the surface and the presence or absence of a bubble represents digital information. Bubble memory is often times referred to as magnetic bubble memory. In yet other embodiments, the non-volatile data storage comprises a random access memory (RAM) with a battery back-up. RAM is memory that permits access to any of its address locations in any desired sequence with similar access time to each location. Typically, RAM is a volatile memory device. However, if a battery backs up RAM, such an arrangement is a non-volatile memory. One of ordinary skill in the art would recognize other equivalents to non-volatile data storage; these equivalents have the ability to store information and for that information to be read out of the memory after a loss of external power to the memory.

One of ordinary skill in the art would also realize thatFIG. 3is merely exemplary and that the tape drive mechanism702, controller704, and non-volatile memory706may or may not be co-located or integrated. The location of these components ofFIG. 5is not material to the use of the present invention.

FIG. 4is a flow chart of the basic cycle of operations of a controller in relation to a tape drive mechanism and a non-volatile memory during normal operation. Block714is an operation that assesses the next instruction in a sequence of instructions for tape drive mechanism702. This assessment may be the reading of the functional state of the tape drive mechanism702stored in the non-volatile memory706in relation to the sequence of instructions that the tape drive mechanism702is performing. This assessment may also include signals from sensors in the tape drive mechanism702that indicate the occurrence of some mechanical event within the tape drive mechanism702. For example, a signal from a sensor located at a take-up reel may indicate that a hub filler is accurately positioned within the take-up reel. In some embodiments of the present invention, the assessment of block714includes consideration of the functional state sent from the non-volatile memory706and signals received from a sensor. After the next instruction in a series of instructions is assessed in block714, this instruction is sent to the tape drive mechanism702for implementation, as shown in block716. The tape drive mechanism702will receive an instruction and perform the corresponding operation. An instruction may include component information, directional information, speed information, or timing information that enables the tape drive mechanism to perform the operation. After the assessed instruction is sent to the tape drive mechanism in block716, the controller stores the functional state of the tape drive in the non-volatile memory, as shown in block706. The functional state that is stored may include a representation of the assessed instruction in relation to the sequence of instructions being performed by the tape drive mechanism702. The functional state stored comprises enough information, such that during reinitialization after a power loss, the tape drive mechanism can resume operation without mechanical failure and with minimal time delay. Upon completion of storage of the functional state in the non-volatile memory in block718, the controller returns to block714to assess the next instruction.

FIG. 5is a flow chart of the exemplary functional relationship between a tape drive mechanism in relation to a controller. In block708, tape drive mechanism702receives an instruction from controller704. The tape drive mechanism702then proceeds to block710to perform the mechanical operation in accordance with the received instruction. After performing the mechanical operation, the tape drive mechanism702returns to block708to receive the next instruction from the controller704. The tape drive mechanism702does not proceed from block708to block710, until an instruction is received from the controller704. The instructions received from the controller704are adequate for the tape drive mechanism702to perform the desired operation.

FIG. 6is a flow chart of the operation of the present invention upon reinitialization of the tape drive mechanism after power loss. In block720, the power to the tape drive is turned on. This power relates to the controller704, the non-volatile memory706, and the tape drive mechanism702. After power on, the tape drive proceeds directly to block714of the flow chart. InFIG. 8, blocks714,716, and718are identical to blocks714,716, and718shown inFIG. 6. In block714, the next instruction is assessed in the sequence of instructions for the tape drive mechanism702. In block716, the assessed instruction is sent to the tape drive mechanism702for implementation. In block718, the functional state of the tape drive mechanism702is stored in the non-volatile memory706. After block718is implemented, control is returned to block714to assess the next instruction. This process continues indefinitely until the next power off.

The present invention provides an improved method and apparatus utilizing non-volatile memory to store the functional state of a tape drive mechanism. The present invention improves the ability for a tape drive to reinitialize after a power loss. Specifically, the tape drive mechanism of the present invention can quickly reinitialize after regaining power following a power loss. The likelihood of a mechanical failure during this reinitialization of the present invention is significantly reduced, compared to the reinitialization of a conventional tape drive.