DE102013112368A1 - Tape storage drive - Google Patents

Abstract

The invention relates to a tape storage drive (1) comprising at least one drive mechanism (4) with at least one head (12) for writing and / or reading data to or from a tape cassette (5) inserted in the tape storage drive (1). The tape storage drive (1) comprises at least one control electronics with a processor (6) for driving the drive mechanism (4) and at least one external interface (2) for connecting the tape storage drive (1) to at least one host system (17). The tape storage drive further comprises at least one nonvolatile semiconductor mass memory (10) connected to the control electronics (3), wherein a control software running on the processor (6) is adapted to store at least a predetermined portion of a tape cassette (5) and / or or store stored data on the non-volatile semiconductor mass memory (10).

Description

The invention relates to a tape storage drive comprising at least one drive mechanism, at least one control electronics and at least one interface for connecting the tape storage drive to at least one host system.

Tape storage drives are widely known in the field of electronic data processing and storage. Compared with other storage media, such as hard disk drives with rotating, magnetic storage media or optical or magneto-optical removable storage media, they offer the particular advantage of low cost per storage capacity, a high data transfer rate when reading and writing large data and a very long shelf life of the storage media. In particular, data stored on magnetic tapes remain readable for decades, while comparable optical storage media, such as recordable CDs or DVDs often become useless after a few years.

For these reasons, tape storage drives and associated tape cartridges are particularly suitable for backup (backup) and archiving, where information must be available in the long term for any access.

A known disadvantage of tape storage drives is that due to the necessary mechanical positioning of the heads used for writing and / or reading over the respective tape section a relatively high access time for reading in data arises.

This disadvantage has only a limited effect on the overall performance when all or a large part of stored data is read in again, for example during a restore of a complete backup.

However, this disadvantage becomes more relevant the more frequently and the less data should be read from a tape storage drive again. So-called archiving systems, in which usually only individual documents are to be read from a comprehensive database, are therefore only conditionally suitable for implementation based on a tape storage drive.

In addition, only a sequential access to the tape drive is possible due to the mechanical limitations, so that in particular no real parallel operation with multiple host systems is possible.

It is an object of the invention to further develop tape storage drives to overcome or mitigate the known disadvantages and associated problems in whole or in part. Preferably, a tape storage drive is described in which access to at least a portion of data stored on a tape cartridge can be speeded up by at least one host system.

The above object is achieved by a tape storage drive comprising at least one drive mechanism having at least one head for writing and / or reading data to and from a tape cassette loaded in the tape storage drive. The tape storage drive comprises at least one control electronics with a processor for controlling the drive mechanism and at least one external interface for connecting the tape storage drive to at least one host system. Furthermore, the tape storage drive comprises at least one connected to the control electronics, non-volatile semiconductor mass memory, wherein running on the processor control software is adapted to store at least a predetermined portion of stored on a tape cassette and / or stored data on the nonvolatile semiconductor mass memory or at least buffer ,

Such a tape storage drive combines the advantages commonly known from tape storage drives of safely and inexpensively storing large amounts of data with the advantages of novel nonvolatile semiconductor mass memory, particularly so-called flash memory or solid state drives (SSD). By at least partially storing data stored or to be stored on a tape cassette in a non-volatile semiconductor memory which is connected to a control electronics of a tape storage drive, the data stored therein can be provided with minimal access time via an external interface.

For example, the external interface is a serial SCSI (SAS), a SCSI over TCP / IP (iSCSI), or a Fiber Channel (FC) interface that allows the tape drive to connect to one or more host systems over a storage network. In contrast, the non-volatile semiconductor mass memory is preferably via an internal interface of the control electronics, such as a memory bus according to the DDR or DDR2 standard or an internal expansion interface such as a PCI Express (PCIe) - or serial ATA interface (SATA) directly or indirectly with connected to the processor.

According to an advantageous embodiment, the control software is set up to store the data last written on a tape cassette at least temporarily in the non-volatile semiconductor mass memory. One of the advantages of this approach is that current written data with a low access time is available for subsequent read requests. For example, in so-called archiving systems with different versions of a file, a most recently written version can be retrieved without physical access to the tape cassette.

According to a further advantageous refinement, the control software is set up to first store data to be written on a tape cassette when receiving a write command from the external interface in the nonvolatile semiconductor mass memory and subsequently to store it on an inserted tape cassette. The described procedure has the advantage that the data are safely stored in the non-volatile semiconductor mass memory at high speed. Compared to other buffers, this has the advantage that the data is retained even in the event of a power failure or other system failure. The subsequent storage on the tape cassette also allows the long-term secure storage of the data.

According to a further advantageous embodiment, the data to be written are initially stored only on the nonvolatile semiconductor mass memory until a predetermined amount of data to be written is stored on the nonvolatile semiconductor mass memory. Upon reaching the predetermined amount, the data to be written is written contiguous to the inserted tape cassette. One of the advantages of this approach is that data can be written to an inserted tape cartridge at a maximum write rate. This avoids, in particular, a tape cassette loading, frequent starting and stopping of the tape cassette.

According to a further embodiment, upon receiving a read command from the external interface for requesting data of a tape cassette, the control software is configured to first check whether the requested data is stored in the nonvolatile semiconductor mass memory and if the requested data is stored in the nonvolatile semiconductor mass memory to read the data stored in the semiconductor nonvolatile memory and return it via the external interface. As a result of this procedure, it is possible to dispense with insertion, positioning and / or reading of a tape cassette during read commands.

According to an advantageous embodiment, the control software is set up to store at least the respectively last requested data in the non-volatile semiconductor mass memory. As a result of this procedure, in particular, data that has already been accessed in the past is stored in the non-volatile semiconductor mass memory so that subsequent accesses can be performed at increased speed.

According to a further embodiment, the control software is adapted to recognize a type of inserted tape cassette and, upon detecting an inserted tape cassette with meta information about data stored on the tape cassette, read the meta information from the tape cassette and store it in the nonvolatile semiconductor mass memory. Tape cartridges and associated tape storage drives of a more recent type, in particular Linear Tape Open (LTO) standard tape storage drives, typically include meta-information, such as linear tape file system (LTFS) file system information, which describes the data stored on the tape cartridge. In this way it is possible to restore the data stored there without additional information on the part of one or more connected host systems. The storage of such data in the nonvolatile semiconductor mass memory enables the accelerated finding of data stored on the tape cassette as well as the performance of various management operations. Since the tape storage drive or its control software has immediate access to the meta-information and can update it accordingly, in particular the simultaneous connection of the tape storage drive with a plurality of host systems via a storage network is possible.

Further embodiments and advantages of the invention are disclosed in the dependent claims and the following detailed description of exemplary embodiments.

The invention will now be described in detail by means of a preferred embodiment with reference to the attached figures. In the figures show:

1 a schematic representation of the structure of a tape storage drive and

2 a schematic representation of a flow chart for responding to requests by a control software tape drive.

1 schematically shows a tape storage drive 1 , The tape storage drive 1 essentially comprises an external interface 2 , an electronic control system 3 and a drive mechanics 4 , Into the tape storage drive 1 can have one or more tape cartridges 5 be inserted. Especially with large tape storage drive systems, it is common to have a so-called robot library with a plurality of tape cassettes 5 provided by means of a robot arm or similar devices in one or more drive mechanisms 4 can be inserted. Of course, it is also possible that the tape storage drive 1 just the manual insertion of a single tape cartridge 5 allowed, as in the 1 shown.

The control electronics 3 usually includes one or more boards with electronic components arranged thereon. In the embodiment according to 1 includes the control electronics 3 including a processor 6 , an input / output module 7 and an interface controller 8th , Via the input / output block 7 controls one on the processor 6 running control software individual components of the drive mechanism 4 at. Via the interface controller 8th the control software receives commands from the external interface 2 and returns any requested data to it. The processor 6 , the input / output block 7 and the interface controller 8th are connected together in a conventional manner via one or more bus systems. In the exemplary embodiment, the components mentioned are, for example, via a PCIe bus 9 connected with each other.

The drive mechanics 4 includes in the illustration according to 1 simplifies a motor 11 and a combined read / write head 12 , The engine is used 11 for positioning a magnetic tape 13 that in the tape cartridge 5 is arranged on two tape rolls or a single winding. In this way, each of the under the read / write head 12 located part of the magnetic tape 13 be read out or written. Optionally includes the drive mechanics 4 furthermore, a reading device 14 to read one into the tape cassette 5 integrated nonvolatile memory module 15 , In the nonvolatile memory module 15 For example, it is a relatively small flash memory with a capacity of 32 kbit (4 KB), the information according to the LTO standard on a tape cartridge identifier 5 or the last tape drive used for reading or writing 1 contains.

The exact function and structure of the drive mechanism 4 as well as the inserted tape cassette 5 as well as the above-mentioned parts of the control electronics 3 correspond essentially to the components known from the prior art and will therefore not be described in detail here.

Furthermore, in the embodiment according to 4 a non-volatile semiconductor mass memory 10 with the processor 6 of the control electronics 3 connected. In the exemplary embodiment, the semiconductor mass memory is designed in the form of an SSD drive and via the PCIe bus 9 with the processor 6 connected. Alternatively, another bus system or a dedicated direct or indirect connection, for example a SATA connection via a suitable interface controller or a part of a chipset, can also be used for the connection. The semiconductor mass memory 10 can also be designed as a flash module, directly via a memory interface, such as a DDR2 interface, with the processor 6 connected is.

In the exemplary embodiment, the non-volatile semiconductor mass memory 10 a relatively large storage capacity of, for example, a few hundred gigabytes up to several Terabytes and serves to store at least a portion of data of a tape cassette 5 currently in the drive mechanics 4 is inserted or has been placed there earlier. The selection of the data to be stored and its use are described below with reference to the flow chart according to 2 described.

In the illustration according to 1 is the tape storage drive 1 over a storage network 16 with two host systems 17 , for example in the form of server computers. For example, this is a Fiber Channel network. Alternatively, the storage drive ( 1 ) also over individual connections, such as SAS connections, with single or multiple host systems 17 be connected.

In the 2 is a method of using the tape storage drive 1 according to 1 represented in the form of a flow chart. The method is controlled by a control software, for example, on the semiconductor memory 10 or other non-volatile storage medium and by the processor 6 is performed.

In a first step S1, the control software receives via the external interface 2 a command. For example, it contains a corresponding SCSI command from a host system via a SAS interface 17 for reading or writing data blocks from or to the tape cassette 5 ,

In a step S2 examines processor 6 First, what kind of command it is. Exemplary is in 2 the execution of a read command, a write command and a command for acquiring directory information shown. Instead of the illustrated separate instruction for acquiring directory information, a sequence of conventional commands, in particular read commands, may also be used to read the directory information from a predetermined part of the tape, for example a tape partition with a predetermined address. Of course, the detection of other commands is possible.

If it was determined in step S2 that it is a write command to write data to one in the tape storage drive 1 inserted tape cassette 5 In step S3, the data transferred together with the command is first transferred to the non-volatile semiconductor mass memory 10 written. Because there is no positioning of the magnetic tape 13 is required, the write command without delay by the processor 6 be executed. Furthermore, it is advantageous that the data is non-volatile in the semiconductor mass memory immediately after writing 10 be present and thus not lost even if any loss of power. Accordingly, the control software via the interface 2 immediately after completion of writing on the semiconductor mass memory 10 confirm the execution of the write command.

In a subsequent, optional step S4, it is checked how many data are already in this way in the non-volatile semiconductor mass memory 10 were written. Will the non-volatile semiconductor mass memory 10 Wholly or partially used as a write buffer, it is checked whether an associated first buffer memory is filled to a predetermined degree. For example, the tape storage drive 1 be set up to write data initially only in the first buffer memory on the non-volatile semiconductor mass memory 10 to write until there is a predetermined amount of data, such as 10 GB, cached. If the first buffer memory offers (again) enough free memory capacity, the writing process is terminated first.

When the first buffer memory finally reaches the predetermined fill level by subsequent write commands, in a subsequent step S5, the information on the semiconductor mass memory is obtained 10 cached data to the tape cartridge 5 written. This is the magnetic tape 13 through the engine 11 moved to the next position to be described and the data then preferably contiguous, that is, without stopping the magnetic tape 13 , via the read / write head 12 on the magnetic tape 13 transfer. In the case that an intermediate storage by the non-volatile semiconductor mass memory 10 is not provided, the step S5 can also be directly connected to the step S3. Occurs when writing on the magnetic tape 13 an interruption of the power supply, an interrupted write operation after restoration of the power supply based on the in the semiconductor mass memory 10 stored data is repeated or continued.

In a further optional step S6, the on the tape cassette 5 written data is deleted from the first buffer memory. This is done in step S6. The deletion of the data in step S6 may be delayed until the storage capacity of the non-volatile semiconductor mass memory 10 is needed for other purposes. In this case, subsequent read requests may also occur after writing the data to the magnetic tape 13 in step S5 still based on the in the first buffer memory of the semiconductor mass memory 10 stored data, as described below.

In step S2, it is determined that the received command is reading data from the tape cassette 5 is requested, it is first checked in a subsequent step S7, whether the requested data in the non-volatile semiconductor mass memory 10 available. For example, physical address information, such as track and segment information, or logical metadata about the requested data, such as a path and file name according to the LTFS standard, may be used to verify that the data is in a predetermined memory area of the semiconductor memory 10 are stored, for example in a write or read buffer.

Are the desired data in the non-volatile semiconductor mass memory 10 before, these are read out there in a step S8 and over the interface 2 returned. The read command is thus completely processed and the method can without time-consuming positioning of the magnetic tape 13 and reading out data via the read / write head 12 to be ended.

Alternatively, that is, if the data is not or not completely in the non-volatile semiconductor mass memory 10 however, in a step S9, the magnetic tape becomes 13 the tape cassette 5 positioned. In addition to the actual positioning of the magnetic tape 13 by fast-forwarding or rewinding, this operation can also be done by inserting another tape cassette 5 through a robotic library. The information necessary for the positioning, such as a volume, a track or a segment, are either taken from the command received in step S1 or are in the non-volatile semiconductor mass memory as metadata, for example according to the LTFS standard 10 saved.

Subsequently, the desired data can be obtained from the tape cassette in a step S10 5 to be read. In particular, this may be above the read / write head 12 correspondingly positioned magnetic tape 13 be read out. The read data are transmitted via the external interface 2 back to the requesting host system 17 Posted.

In an optional step S11, the returned data is additionally stored in the non-volatile semiconductor mass memory 10 stored. For example, the data may be stored in a second buffer, a read buffer. This approach is particularly advantageous in archival systems because the likelihood of once-read data being accessed is greater than the probability of any other on the same tape cartridge 5 to access stored data.

2 finally shows an example of the reading of directory information. If a corresponding command is detected in step S2, in a subsequent step S12 in a predetermined memory area of the semiconductor mass memory 10 stored metadata and according to the request via the interface 2 returned.

Preference is already given when inserting a tape cassette 5 examines whether it contains appropriate metadata, such as data according to the LTFS standard. For this purpose, for example, are on the non-volatile memory module 15 stored information. If corresponding meta-information is detected, for example a tape partition with LTFS data contained therein, these are read in at an appropriate time and on the non-volatile semiconductor mass memory 10 cached. For example, the reading can be done immediately after inserting the tape cassette 5 or in an idle state where no host system 17 on the tape storage drive 1 accesses.

One of the advantages of this procedure is that when connecting the tape storage drive 1 over a storage network 16 to several host systems 17 parallel accesses from the different host systems 17 can be edited without requiring repeated reading of the LTFS information from a corresponding partition of an LTO tape storage drive. In addition, the LTFS information can be stored centrally in the tape storage drive 1 be stored, allowing a re-storage of this information by the individual host systems 17 is not required. This central storage makes sharing the LTFS data an LTO tape cartridge 5 in the tape storage drive 1 allows, as there is no inconsistency of otherwise by the individual host systems 17 Caching metadata can come.

In addition to the regarding the 2 described procedure for filling the non-volatile semiconductor mass memory 10 It is also possible to use other methods known per se for buffering data. In particular, displacement algorithms known from the field of hierarchical memory systems can be used to determine the memory contents of the nonvolatile semiconductor mass memory 10 be used.

Alternatively, it is also possible from an external host system 17 over the interface 2 Explicitly specify which data is preferred in the nonvolatile semiconductor memory 10 should be saved. In this way, through a suitable application programming interface (API), applications can be given full control over which data is to be accessed very quickly to increase the performance of the tape storage drive of the present invention 1 to optimize.

LIST OF REFERENCE NUMBERS

1

Tape storage drive

2

external interface

3

control electronics

4

Drive mechanics

5

tape cartridge

6

processor

7

Input / output port

8th

Interface Controller

9

PCIe bus

10

non-volatile semiconductor mass memory

11

engine

12

Read / write head

13

magnetic tape

14

reading device

15

non-volatile memory chip

16

Storage networking

17

host system

S1 to S12

steps

Claims (10)

Tape Storage Drive ( 1 ), comprising at least one drive mechanism ( 4 ) with at least one head ( 12 ) for writing and / or reading Data to or from one in the tape storage drive ( 1 ) inserted tape cassette ( 5 ); At least one control electronics ( 3 ) with a processor ( 6 ) for controlling the drive mechanism ( 4 ); At least one external interface ( 2 ) for connecting the tape storage drive ( 1 ) to at least one host system ( 17 ); and - at least one with the control electronics ( 3 ), non-volatile semiconductor mass memory ( 10 ), with one on the processor ( 6 ) running control software is adapted to at least a predetermined part of on a tape cassette ( 5 ) stored and / or stored data on the non-volatile semiconductor mass memory ( 10 ) save. Tape Storage Drive ( 1 ) according to claim 1, wherein the external interface ( 2 ) for connecting the tape storage drive ( 1 ) to at least one host system ( 17 ) as an interface for a storage network ( 16 ), in particular as a SCSI, iSCSI, SAS or Fiber Channel interface is formed. Tape Storage Drive ( 1 ) according to claim 1 or 2, wherein the non-volatile semiconductor mass memory ( 10 ) via an internal interface of the control electronics ( 3 ), in particular a DDR, PCI Express or SATA interface, with the processor ( 6 ) or an interface module of the control electronics ( 3 ) connected is. Tape Storage Drive ( 1 ) according to one of Claims 1 to 3, in which the control software is set up in each case last on an inserted tape cassette ( 5 ) at least temporarily in the non-volatile semiconductor mass memory ( 10 ) save. Tape Storage Drive ( 1 ) according to one of claims 1 to 4, in which the control software is set up to receive a write command from the external interface ( 2 ) on a tape cassette ( 5 ) data to be written first in the non-volatile semiconductor mass memory ( 10 ) and subsequently to an inserted tape cassette ( 5 ) to write. Tape Storage Drive ( 1 ) according to claim 5, wherein the control software is set up to write data initially only on the non-volatile semiconductor mass memory ( 10 ) until a predetermined amount of data to be written on the non-volatile semiconductor mass memory ( 10 ) is stored, and upon reaching the predetermined amount, the data to be written contiguous to the inserted tape cassette ( 5 ) to write. Tape Storage Drive ( 1 ) according to one of claims 1 to 6, in which the control software is set up to receive a read command from the external interface ( 2 ) for requesting data from a tape cassette ( 5 ) first check whether the requested data in the non-volatile semiconductor mass memory ( 10 ) and if the requested data in the non-volatile semiconductor mass memory ( 10 stored in the non-volatile semiconductor mass memory ( 10 ) and via the external interface ( 2 ). Tape Storage Drive ( 1 ) according to claim 7, wherein the control software is adapted to at least the respectively last requested data in the non-volatile semiconductor mass memory ( 10 ) save. Tape Storage Drive ( 1 ) according to one of claims 1 to 8, wherein the control software is adapted to a type of inserted tape cassette ( 5 ) and recognizing an inserted tape cassette ( 5 ) with meta-information on the tape cartridge ( 5 ) stored meta information from the tape cartridge ( 5 ) and in the non-volatile semiconductor mass memory ( 10 ) save. Tape Storage Drive ( 1 ) according to claim 9, wherein the drive mechanism ( 4 ) according to the Linear Tape Open standard and in which the control software is set up on an inserted LTO tape cassette ( 5 in the non-volatile semiconductor mass memory (FIG. 10 ) and via the external interface ( 2 ) based on the stored LTFS metadata.

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