CROSS-REFERENCE TO RELATED APPLICATIONS

A storage library is described including a first tape drive that is identified as a target tape drive to a host via a first address and a second tape drive that is masked from being identified by the host. The storage library further includes a controller that is linked with a switch system that shifts the first address to the second drive from the first drive such that after the shift, the second drive is identified as the target drive to the host and the first drive is masked from being identified by the host.

Starr, Matthew Thomas (Lafayette, CO, US)

Goberis, Michael Gerard (Broomfield, CO, US)

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Spectra Logic Corporation (Boulder, CO, US)

Storage area network methods and apparatus for communication and interfacing with multiple platforms

System and method for the prevention of corruption of networked storage devices during backup data recovery

Media library with failover capability

1. A storage library comprising: a first drive identifiable as a target drive to a host via a first address; a second drive; the first drive and the second drive influenced by a switching system that reassigns the first address to identify the second drive as the target drive to the host; a plurality of removable storage elements adapted to be received by either the first drive or the second drive in a cooperating relationship capable of performing storage operations; a first drive bay that accommodates the first drive and a second drive bay that accommodates the second drive wherein the first address is either maintained by the first drive bay, when identifying the first drive as the target drive, or is maintained by the second drive bay, when identifying the second drive as the target drive.

2. The storage library of claim 1 wherein the target drive is further identifiable by at least a second address used in conjunction with the first address.

3. The storage library of claim 1 wherein the first address is a storage element address and wherein the target drive is further identifiable via a World Wide Name.

4. The storage library of claim 3 wherein the target drive is further identifiable via a Serial Number associated with the first drive.

5. The storage library of claim 1 wherein the second drive is masked from being identifiable to the host until the second drive is switched to the target drive and the first drive is masked from being identifiable to the host after the second drive is switched to the target drive.

6. The storage library of claim 1 wherein the switching system reassigns the first address from the first drive bay to the second drive bay.

7. The storage library of claim 6 wherein the switching system reassigns the first address from the first drive bay to the second drive bay when the first drive is disabled.

8. The storage library of claim 1 wherein the switching system reassigns the first address without interrupting power to the storage library.

9. The storage library of claim 1 wherein the switching system reassigns the first address from the first drive bay to the second drive bay without the host having any knowledge of the address switch.

10. The storage library of claim 1 wherein the switching system is comprised by a processing device.

11. The storage library of claim 1 wherein the first address is maintained by either the first drive or the second drive.

12. The storage library of claim 1 wherein the first drive is selected from a group consisting of: a disc drive docking station, a disc drive magazine docking station, a solid state storage device docking station, and a drive configured to receive independent storage discs.

13. The storage library of claim 1 wherein the first and the second drives are each tape drives and the plurality of removable storage element are tape cartridges.

14. The storage library of claim 1 wherein at least one of the removable storage elements is selected from a group consisting of: disc drives adapted for mobility from standard disc drives, mobile disc drive magazine, solid state storage devices adapted for mobility, independent storage discs.

15. The storage library of claim 1 wherein the switching system is comprised by the storage library.

16. A storage library comprising: a first drive identified as a target drive to a host via at least a first address; a second drive that is masked from being identified by the host when the first drive is the target drive; a controller linked with a switch system that is configured to shift the at least first address to the second drive from the first drive wherein after the shift the second drive is identified as the target drive to the host and the first drive is masked from being identified by the host; and a plurality of removable storage element adapted to cooperate with either the first drive or the second drive to perform storage operations; a first drive bay that accommodates a first drive and a second drive bay that accommodates a second drive; a first address that is either maintained by the first drive bay, when identifying the first drive as the target drive, or is maintained by the second drive bay, when identifying the second drive as the target drive.

17. The storage library of claim 16 further comprising a means for switching from the target drive from the first drive to the second drive.

18. The storage library of claim 16 further comprising a means for masking a drive from the host.

19. A method for directing storage traffic in a storage library comprising: indentifying a first drive as a target drive to a host via at least a first address; reassigning the first address to a second drive so that the second drive is identified as the target drive to the host, wherein the at least a first address is maintained by a drive bay that accommodates one of the drives; loading one of a plurality of removable storage elements included in the storage library in a cooperating relationship with the target drive; and receiving storage related communications from the host directed to the target drive.

20. The method of claim 19 wherein the reassigning step is performed after the first drive is disabled.

21. The method of claim 20 further comprising replacing the first drive with a third drive and reassigning the first address to the third drive without altering power to the storage library.

22. The method of claim 19 wherein the host has no knowledge that the target drive changed from the first drive to the second drive.

23. The method of claim 19 wherein the target drive is identified via a storage element address maintained by the library and a Serial Number and World Wide Name associated with the target drive.

24. The method of claim 19 wherein the reassigning step is accomplished by at least one command executed by touching a touch screen associated with the storage library.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention relates generally to shifting identity from one storage drive, such as a tape drive, to another storage drive without a host having any knowledge of the shift in identity.

Tape libraries, which generally house a multitude of tape cartridges, are often equipped with plurality of tape drives which, on occasion, may fail. When failure of a tape drive occurs, the tape library is shut down in order to swap the failed drive with a functional drive. The time over which the tape library is shut down is referred to downtime. FIG. 1 is used herein to assist in the description of how failed tape drives are replaced with functional tape drives.

FIG. 1 is an illustration of a tape library100that is linked with a first host102and a second host104via first switch system106and a second switch system108. The tape library100is illustratively shown with twelve drive bays110wherein each drive bay110is configured to accommodate a tape drive112. The tape library100possesses eight tape drives112and has four empty drive bays110, each available to receive a tape drive
112. Each tape drive112is configured with a Serial Number and a World Wide Name. Hence, as illustratively shown, drive B114is linked to switch1and switch2and possesses a Serial Number (SN) and World Wide Name (WWN), which for purposes of illustration can be SN 1234 and WWN ABCD1234 respectively. If drive B114fails, drive B114is removed from the associated drive bay110and a new similar tape drive is installed with a new Serial Number and World Wide Name, such as SN 5678 and WWN EFGH5678, respectively. The tape library100needs to be rebooted in order for the host computers102and104to recognize that the tape library100possesses a new functional tape drive with SN 5678 for and WWN EFGH5678. The acts of replacing drive B114and rebooting the library100create a lengthy downtime whereby the tape library100is unavailable for storage operations.

Some tape library systems have improved the necessity to reboot the tape library by assigning the tape drive Serial Number and World Wide name to the drive bay instead of the tape drive. For purposes of illustration conforming similarly to the aforementioned example, the drive bay116can been assigned the SN 1234 and WWN ABCD1234. That way, if a new tape drive is installed as a replacement to a failed tape drive, the new tape drive will be recognized by host computers102and104as being the tape drive possessing the Serial Number 1234 and World Wide name ABCD1234, thus, eliminating the need to reboot of the tape library100. Nonetheless, critical time is still lost when the failed tape drive is replaced by a functional tape drive.

In an effort to reduce downtime associated with replacing a failed tape drive with a functional tape drive within a tape library, both methods and apparatuses are disclosed herein. It is to innovations related to this subject matter that the claimed invention is generally directed.

The present invention generally relates to a storage library that possesses at least one spare drive that is masked from a host and overcomes the disadvantages and limitations of the prior art by shifting identity from one storage drive to the spare storage drive without the host having any knowledge of the shift in identity.

One embodiment of the present invention can therefore comprise a storage library comprising: a first drive identifiable as a target drive to a host via a first address; a second drive; the first drive and the second drive influenced by a switching system that reassigns the first address to identify the second drive as the target drive to the host; and a plurality of removable storage elements adapted to be received by either the first drive or the second drive in a cooperating relationship capable of performing storage operations.

Another embodiment of the present invention can therefore comprise a storage library comprising: a first drive identified as a target drive to a host via at least a first address; a second drive that is masked from being identified by the host when the first drive is the target drive; a controller linked with a switch system that is configured to shift the at least first address to the second drive from the first drive wherein after the shift the second drive is identified as the target drive to the host and the first drive is masked from being identified by the host; and a plurality of removable storage element adapted to cooperate with either the first drive or the second drive to perform storage operations.

Yet another embodiment of the present invention can therefore comprise a method for directing storage traffic in a storage library comprising: indentifying a first drive as a target drive to a host via at least a first address; reassigning the first address to a second drive so that the second drive is identified as the target drive to the host; loading one of a plurality of removable storage elements included in the storage library in a cooperating relationship with the target drive; and receiving storage related communications from the host directed to the target drive.

FIG. 1A is a prior art pictorial representation of a tape library that presents tape drives to several host systems.

FIG. 2 is a block diagram of a data storage arrangement constructed in accordance with an embodiment of the present invention.

FIGS. 3A and 3B are block drawings of certain specific elements from FIG. 2 used to illustrate an embodiment of the present invention.

FIG. 4A-4D are block diagrams illustrating various embodiments of multiple global spare configurations consistent with embodiments of the present invention.

FIG. 5A is a block diagram illustrating an embodiment of identifying drives via drive bay addresses consistent with embodiments of the present invention.

FIG. 5B is a block diagram illustrating an embodiment of switching drive identity via drive bay addresses consistent with embodiments of the present invention.

FIG. 6 is a block diagram illustrating a method to practice an embodiment of the present invention.

FIGS. 7A and 7B show different perspective views of a Spectra Logic e-950 storage library without a cover in which some embodiments of the present invention can be commercially practiced.

Referring to the drawings in general, and more specifically to FIG. 2, shown therein is a block diagram of a data storage arrangement200constructed in accordance with an embodiment of the present invention. In what follows, similar or identical structures may be identified using identical callouts.

The data storage arrangement200includes a host computer203in communication232with a storage system201via a primary communication interface processor device (I/F)230that includes a host port (not shown). The host computer203is one exemplary embodiment of a consumer of data; other embodiments can also include a second storage system, similar to storage system201, or a streaming output device such as a video server, just to name some examples. A consumer of data is an entity, or entities, that transmits data or receives data for storage elsewhere, i.e., a consumer of data is generally capable of taking in and/or sending out data. For example, a host computer203is a consumer of data when receiving data (or sending data, such as to the storage system201), and a storage system201is a consumer of data when receiving and sending data to another entity wherein the data is stored. The host computer203can be a personal computer, a main frame computer, a server, or any computer system capable of communication with the storage system201, just to name a few examples. The communication path232facilitates communication between the host computer203and the storage system201. The means for communication can be accomplished by a dedicated pathway (such as a SCSI [Small Computer Systems Interface] cabled connection) or, in an alternative embodiment, a pathway over a network (such as a LAN, WAN, or other communication architecture), for example. Furthermore, the communication path232can be in the form of a wire line pathway, wireless, or a combination thereof, for example.

The storage system201, which may also considered a data storage library by those skilled in the art, is illustratively shown as generally including a shelf system211, a first robotic transport unit214and a second robotic transport unit216, four removable storage elements202,204,206and208, four drives218,220,222and224, a switch system226, a storage system Central Processing Unit (CPU)228and I/F230. As one skilled in the art will recognize, the block diagram of the storage system201shows the primary elements of interest for purposes of simplicity. As such, certain necessary structures and components for the aforementioned elements to properly function are omitted from the detailed description; however, such integrating structures and components do exist within the scope of the present invention. For example, in practice, the storage system201includes all of the necessary wiring, user interface panels, plugs, modular components, entry and exit port(s) to introduce (or remove) removable storage elements into the storage system201
, fault protectors, uninterruptable power supplies, processors, busses, robotic transport unit tracks, indication lights, and so on, in order to function as a data storage library.

As shown in the illustrative embodiment, the shelf system111possesses a first shelf210and a second shelf212wherein the first and second shelves220and212are adapted to support the removable storage elements A202, B204, C206and D208. The shelf system211can possess a single shelf or multiple shelf levels. The shelf system211can be located along one side of the storage system201, as illustratively shown, or optionally in different locations, such as along opposing walls, for example. Furthermore, the shelf system211can provide more tailored accommodating locations adapted specifically to one or more removable storage elements, such as a slot or indentation that matches a removable storage elements footprint. The removable storage element is a storage element that has been adapted for repetitive mobility by a robotic transport unit. The removable storage element can be a disc drive adapted for mobility, a disc drive magazine adapted for mobility, wherein the disc drive magazine comprises a plurality of disc drives, a solid state memory device adapted for mobility, such as a flash memory device, a tape cartridge, a tape magazine comprising a plurality of tape cartridges, an optical disc, a magazine comprising a plurality of optical discs, an independent storage disc, such as a magneto-optical disc or magnetic disc or alternative memory disc used as a storage medium, a magazine comprising a plurality of independent storage discs, or another type of storage device capable of storing data that is adapted for mobility. Further, the removable storage elements are removable from the storage system201, for example, a tape cartridge, or other mobile storage element, is a removable storage element that can be stored in a location external to the storage system201in a vault. Hence, a removable storage element, also called a mobile storage element herein, is a storage element that is intended to be and capable of being moved and engaged with a drive cyclically and frequently. A standard disc drive alone, without modification, for example, is not intended to be frequently moved within or outside of a library (or computer system) and, hence, is not considered removable/mobile in the spirit of the inventive embodiments used herein unless adapted with a feature or features that facilitate mobility, such as high cycle electrical contacts, for example. A drive herein is a device that is adapted to receive and substantially support a removable storage element via an opening in the drive such that when cooperatively linked a read and write relationship is formed (i.e., storage operations are facilitated between the drive and the removable storage medium). Some examples of a drive include, a disc drive docking station, a tape drive, disc drive magazine docking station. A socket adapted to receive a plug, such as a serial port and serial port connector, is not considered to be a docking station, rather, simply a socket.

With continued reference to FIG. 2, the storage system201possesses a first robotic transport unit214and a second robotic transport unit216wherein the first robotic transport unit214is illustratively shown transporting magazine B204between a drive218and the shelf system212, and a second robotic transport unit216that is available for transporting a removable storage element. The term robot may be used, herein, to abbreviate the term robotic transport unit without departing from the scope and spirit of the present invention. In one embodiment, the robots214and216are adapted to move between the first shelf210and the second shelf212and all of the drives218,220,222and224. Though the robots214and216are illustratively shown as block diagrams, one commercial example of a robotic transport unit can be seen in a commercial example of a storage system, namely, a T-950 library manufactured by Spectra Logic Corp., of Boulder, Colo. The T-950 robotic transport units traverse the T-950 library along a track system and move vertically via an elevator system integrated with each robot transport unit. Furthermore, the T-950 robotic transport units possess an integrated picker system that grasps removable storage elements from a shelf system or from a drive to be moved via the associated robotic transport unit. The integrated picker system further is capable of disposing a removable storage element to the shelf system or to a drive. In the illustrative embodiments, the robot merely provides transportation of the removable storage elements from a location associated with the shelf system211to a drive wherein the robot may provide the added feature of depositing a removable storage element on the shelf system212and/or loading the removable storage element in a cooperating relationship with a drive such that data can be read to and written from the removable storage element via the drive. In optional configurations, a loading feature can reside with each drive as opposed to a picker unit integrated with a robotic transport unit.

The storage system201illustratively shows four drives218,220,222and224, however, in optional embodiments, the library may possess more drives or fewer drives. A drive herein is considered to be a device that forms a cooperating relationship with a removable storage element such that data can be written to and from the removable storage element wherein the removable storage element serves as a mass storage device. A drive herein is not merely a socket device and cable, such as that which is used for connecting a disk drive to a computer system. Examples of various drives used within the scope and spirit of this invention include: a tape drive that is adapted to receive tape cartridges, a disk drive docking station which receives a disk drive adapted for mobility that when paired forms a cooperating read and write relationship, such as a disk drive inside an exterior casing with electrical contacts designed for high cycle contacting, and a disk drive magazine docking station which receives a removable disk drive magazine, as exemplified in U.S. Application No. 2006/0132964 to Lau et al, a Compact Disk (CD) drive used with a CD.

In the interest of simplifying the description, the storage system201and the components therein will be described in terms of tape library embodiments hereinafter. Hence, a tape library201will be used as an embodiment of the storage system201, tape drives will be used as an embodiment for the drives, and tape cartridges will be used as an embodiment for removable storage elements. The tape library and tape library component embodiments may share common callouts.

With continued reference to FIG. 2, communication protocol is bridged between the host computer203and the tape library201via the I/F230. That is, the host computer203may communicate over one protocol and the tape library201may use a different protocol, hence, the I/F203facilitates communication to occur between the tape library201and the host computer203. One commercial example of an I/F system is a Fibre Quad Interface Processor (FQIP) manufactured by Spectra Logic Corporation. The FQIP facilitates communication between a host computer system which uses a fibre protocol and the Spectra Logic storage library which uses a SCSI-like Computer Area Network (CAN) protocol unique to the Spectra Logic Corporation to communicate with the components comprised therein over the librarys internal Computer Area Network bus. The I/F230is linked to the CPU228, along with most electrical components within the tape library201via a CAN (not shown) specific to the tape library201. The I/F230is illustratively shown in communication via the two way arrow232with the host computer203. Generally, the host computer203issues a read element status request used to determine the identity and volume of tape cartridges, the number of tape drives and their respective logical unit numbers, the number of robots, tape cartridges going in and out of the library201. More specifically, the libra
ry201maintains element addresses which include storage element addresses, data transfer element addresses, import/export element addresses, and media transport element addresses.

FIG. 3A is a block drawing of specific elements from FIG. 2 used herein to illustrate an embodiment of the present invention. As shown, the library201has a first tape drive218that possesses an element address of [0100], Serial Number (SN): AA1 and World Wide Name (WWN): 100, and that resides in drive bay [001]. The first tape drive218has an opening304adapted to receive a tape cartridge (not shown) in order to perform storage operations. Storage operations include reading and writing data to and from the tape cartridge, as well as indexing across the tape or performing other operations when the tape cartridge is in a cooperating relationship with the drive218. The drive bays (generically element302) are locations in the library201that hold and support a drive218, for example. A drive bay302is adapted to receive a drive218(or a drive sled that contains a drive, as discussed later) and interconnect with the drive218such that, when the drive218is installed in a drive bay302(forming a cooperating relationship), connectivity, such as power and communication, are provided to the drive218. Drives can be exchanged or moved from one drive bay302to another. Drive bay [004] does not possess a drive and is available to receive a fourth drive, for example. The library201further comprises a second drive220that possesses an element address of [0101], SN: AB3 and WWN: 101, and resides in drive bay [002] and a third drive222that is masked from being viewed by the host203.

The element addresses [0100] and [0101] are viewable by the host203via a number designation that is internally known by the library201. For example, the library201is illustratively shown having three drives218,220and222wherein only the first drive218and the second drive220are revealed to the host203via the element address [0100] and element address [0101], respectively. In some instances, the host203may rename or renumber the element addresses in a designation that is better suited for the host203, such as 1, 2, 3, etc., however, in the interests of simplicity, the element addresses will be described as illustratively shown.

The drives can be connected to the host203separately and additionally from the connection that makes the drives internally known by the library201through element addresses, in what is known to those skilled in the art as a direct connect drive. The direct connect drive can be viewed by the host203via the drives Serial Number (SN) and World Wide Name (WWN) over the host interface bus through the I/F230. Optionally, a drive can be connected to an intermediate interface device, such as a Spectra Logic FQIP. Any modification of the drive or drives status can occur in the librarys background and be masked from the host201, as shown by a third drive222.

A Read-Element-Status (loosely called an inventory) command is part of the inventory request made by the host203wherein the host203identifies all elements having element addresses within the library201. The host203further identifies the tape drives possessing a WWN and SN maintained by the library201as seen over the host interface bus230and232. The host203draws correspondence between certain tape drive element addresses and WWNs and SNs, such as element address [0100], WWN: 100 and SN: AA1 which all correspond to the first drive218, for example. Hence, in practicality, the host203identifies additional data transfer devices, i.e. tape drives, via the interface230(i.e. fibre or SCSI). The host203maps element address [0100] to WWN and SN of the drive. When the bus is over fibre channel, it is a fibre address, and on SCSI, it is a SCSI address, for example. There is a one to one correspondence between the drives found by the host203and those drives that have element addresses maintained, or inventoried, by the library201.

The masked drive222in drive bay 003 is a spare drive that is masked from the host203in what herein is referred to as a global spare drive. The global spare drive222is hidden in the library201in that it does not have an assigned data transfer element address. The global spare222is further disabled from being identified over the host interface bus230and232, i.e. the global spare222is turned off, in hibernation, in some other inactive stasis, or otherwise in an off-line state. The library201can display that there is a drive222present in drive bay [003] through a graphical user interface (not shown) located on an exterior panel associated with the library201. Optionally, the global spare222may be seen externally as an element within drive bay222, for example, by the manufacturer or library owner via a pathway that is different from the host203. In an optional embodiment, the global spare drive222possesses a data transfer element address that is masked from the host203but is viewable by other privileged users.

In the present embodiment, the first drive218can be disabled and the identity of the first drive218can be shifted to the global spare drive222(not necessarily in that order) as illustratively shown in FIG. 3B. Hence, the first drive218is no longer identified by the host203. As shown, the identity of the first drive218, originally associated with element address [0100], SN: AA1 and WWN: 100, is now assumed by the