Mechanism for transparent virtual tape engines restart

1. A method for restarting virtual tape engines (VTEs), comprising:

receiving a restart request comprising a VTE configuration for a VTE; and

processing the restart request to restart the VTE by:

storing the VTE configuration in a shared data buffer (SDB) residing on the VTE;

detaching a set of virtual tape drives from the VTE;

preserving a tape drive state (TDS), a set of tape drive processes (TDPs), and input/output (I/O) network traffic associated with each virtual tape drive of the set of virtual tape drives, in the SDB; and

after the preserving, restarting the VTE.

2. The method of claim 1 , wherein detaching the set of virtual tape drives from the VTE comprises:

issuing a busy notification to a mainframe operatively connected to the VTE;

after confirming reception of the busy notification from the mainframe, for each virtual tape drive of the set of virtual tape drives on the VTE:

severing a connection between the virtual tape drive and a mainframe interface operatively connected to the mainframe;

suspending the set of TDPs supporting the virtual tape drive;

suspending a set of outgoing network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of outgoing network packets is awaiting transmission to the mainframe;

suspending a set of incoming network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of incoming network packets is awaiting processing by the VTE;

obtaining the TDS comprising a current state of the virtual tape drive; and

unmounting the virtual tape drive from a directory within a VTE filesystem residing on the VTE.

3. The method of claim 1 , further comprising:

following a re-activation of the VTE after the restarting:

obtaining the VTE configuration from the SDB;

reading the VTE configuration to identify a restore from saved state (RSS) flag specified therein;

determining that the RSS flag is enabled; and

based on the determining, configuring the VTE using a preserved state.

4. The method of claim 3 , wherein configuring the VTE using the preserved state comprises:

for each virtual tape drive of the set of virtual tape drives:

obtaining the TDS for the virtual tape drive from the SDB;

re-creating the virtual tape drive using the TDS; and

re-creating a tape drive agent (TDA) responsible for the virtual tape drive, and

after re-creating each virtual tape drive and each TDA:

re-attaching the set of virtual tape drives to the VTE, wherein restoring the preserved state comprises at least the re-creating and the re-attaching.

5. The method of claim 4 , wherein re-attaching the set of virtual tape drives to the VTE comprises:

for each virtual tape drive of the set of virtual tape drives:

re-establishing a connection between the virtual tape drive and a mainframe interface operatively connected to a mainframe;

unsuspending the set of TDPs supporting the virtual tape drive;

unsuspending a set of outgoing network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of outgoing network packets is awaiting transmission to the mainframe;

unsuspending a set of incoming network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of incoming network packets is awaiting processing by the VTE; and

re-mounting the virtual tape drive to a directory within a VTE filesystem residing on the VTE, and

after re-mounting each virtual tape drive of the set of virtual tape drives:

issuing a ready notification to the mainframe through the mainframe interface.

6. The method of claim 1 , further comprising:

following a re-activation of the VTE after the restarting:

obtaining the VTE configuration from the SDB;

reading the VTE configuration to identify a restore from saved state (RSS) flag specified therein;

determining that the RSS flag is disabled; and

based on the determining, configuring the VTE using an initial state.

7. The method of claim 6 , wherein configuring the VTE using the initial state comprises:

for each new virtual tape drive of a set of new virtual tape drives specified in the VTE configuration:

extracting a tape drive configuration (TDC) for the new virtual tape drive from the VTE configuration;

creating the new virtual tape drive using the TDC; and

creating a new tape drive agent (TDA) responsible for the new virtual tape drive, and

after creating each new virtual ape drive and each new TDA:

attaching the set of new virtual tape drives to the VTE, wherein setting the initial state comprises at least the creating.

8. The method of claim 7 , wherein attaching the set of new virtual tape drives to the VTE comprises:

for each new virtual tape drive of the set of new virtual tape drives:

establishing a connection between the new virtual tape drive and a mainframe interface operatively connected to a mainframe; and

mounting the new virtual tape drive to a directory within a VTE filesystem residing on the VTE, and

after mounting each new virtual tape drive of the set of new virtual tape drives:

issuing a ready notification to the mainframe through the mainframe interface.

9. A system, comprising:

a requesting entity; and

a virtual tape solution (VTS) operatively connected to the requesting entity, and programmed to:

receive, from the requesting entity, a restart request comprising a set of virtual tape engine (VTE) IDs and a set of VTE configurations; and

process the restart request to restart a set of VTEs by:

for each VTE of the set of VTEs:

identifying the VTE using a VTE ID of the set of VTE IDs, and

delegating, to the VTE, a VTE configuration of the set of VTE configurations.

10. The system of claim 9 , wherein each VTE of the set of VTEs is a server forming the VTS.

11. The system of claim 9 , wherein each VTE of the set of VTEs comprises:

a mainframe interface;

a set of virtual tape drives operatively connected to the mainframe interface;

a set of tape drive agents (TDAs) responsible for the set of virtual tape drives;

a tape drives manager (TDM) responsible for the set of TDAs;

a mainframe interface driver (MID) managing communications between the mainframe interface and the set of virtual tape drives;

a VTE kernel overseeing at least the TDM and the MID; and

a shared data buffer (SDB) for storing at least the VTE configuration.

12. The system of claim 9 , further comprising:

a mainframe operatively connected to each VTE of the set of VTEs.

13. A non-transitory computer readable medium (CRM) comprising computer readable program code, which when executed by a computer processor, enables the computer processor to:

receive a restart request comprising a VTE configuration for a VTE; and

process the restart request to restart the VTE by:

storing the VTE configuration in a shared data buffer (SDB) residing on the VTE;

detaching a set of virtual tape drives from the VTE;

preserving a tape drive state (TDS), a set of tape drive processes (TDPs), and input/output (I/O) network traffic associated with each virtual tape drive of the set of virtual tape drives, in the SDB; and

after the preserving, restarting the VTE.

14. The non-transitory GRIM of claim 13 , wherein to detach the set of virtual tape drives from the VTE, the computer readable program code, which when executed by the computer processor, enables the computer processor to:

issue a busy notification to a mainframe operatively connected to the VTE;

after confirming reception of the busy notification from the mainframe, for each virtual tape drive of the set of virtual tape drives on the VTE:

sever a connection between the virtual tape drive and a mainframe interface operatively connected to the mainframe;

suspend the set of TDPs supporting the virtual tape drive;

suspend a set of outgoing network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of outgoing network packets is awaiting transmission to the mainframe;

suspend a set of incoming network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of incoming network packets is awaiting processing by the VTE;

obtain the TDS comprising a current state of the virtual tape drive; and

unmount the virtual tape drive from a directory within a VTE filesystem residing on the VTE.

15. The non-transitory CRM of claim 13 , further comprising computer readable program code, which when executed by the computer processor, enables the computer processor to:

following a re-activation of the VTE after the restarting:

obtain the VTE configuration from the SDB;

read the VTE configuration to identify a restore from saved state (RSS) flag specified therein;

determine that the RSS flag is enabled; and

based on the determining, configure the VTE using a preserved state.

16. The non-transitory CRM of claim 15 , wherein to configure the VTE using the preserved state, the computer readable program code, which when executed by the computer processor, enables the computer processor to:

for each virtual tape drive of the set of virtual tape drives:

obtain the TDS for the virtual tape drive from the SDB;

re-create the virtual tape drive using the TDS; and

re-create a tape drive agent (TDA) responsible for the virtual tape drive, and

after re-creating each virtual tape drive and each TDA:

re-attach the set of virtual tape drives to the VTE, wherein restoring the preserved state comprises at least the re-creating and the re-attaching.

17. The non-transitory CRM of claim 16 , wherein to re-attach the set of virtual tape drives to the VTE, the computer readable program code, which when executed by the computer processor, enables the computer processor to:

for each virtual tape drive of the set of virtual tape drives:

re-establish a connection between the virtual tape drive and a mainframe interface operatively connected to a mainframe;

unsuspend the set of TDPs supporting the virtual tape drive;

unsuspend a set of outgoing network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of outgoing network packets is awaiting transmission to the mainframe;

unsuspend a set of incoming network packets of the I/O network traffic associated with the virtual tape drive, wherein the set of incoming network packets is awaiting processing by the VTE; and

re-mount the virtual tape drive to a directory within a VTE filesystem residing on the VTE, and

after re-mounting each virtual tape drive of the set of virtual tape drives:

issue a ready notification to the mainframe through the mainframe interface.

18. The non-transitory CRM of claim 13 , further comprising computer readable program code, which when executed by the computer processor, enables the computer processor to:

following a re-activation of the VTE after the restarting:

obtain the VTE configuration from the SDB;

read the VTE configuration to identify a restore from saved state (RSS) flag specified therein;

determine that the RSS flag is disabled; and

based on the determining, configure the VTE using an initial state.

19. The non-transitory CRM of claim 18 , wherein to configure the VTE using the initial state, the computer readable program code, which when executed by the computer processor, enables the computer processor to:

for each new virtual tape drive of a set of new virtual tape drives specified in the VTE configuration:

extract a tape drive configuration (TDC) for the new virtual tape drive from the VTE configuration;

create the new virtual tape drive using the TDC; and

create a new tape drive agent (TDA) responsible for the new virtual tape drive, and

after creating each new virtual tape drive and each new TDA:

attach the set of new virtual tape drives to the VTE, wherein setting the initial state comprises at least the creating.

20. The non-transitory CRM of claim 19 , wherein to attach the set of new virtual tape drives to the VTE, the computer readable program code, which when executed by the computer processor, enables the computer processor to:

for each new virtual tape drive of the set of new virtual tape drives:

establish a connection between the new virtual tape drive and a mainframe interface operatively connected to a mainframe; and

mount the new virtual tape drive to a directory within a VTE filesystem residing on the VTE and

after mounting each new virtual tape drive of the set of new virtual tape drives:

issue a ready notification to the mainframe through the mainframe interface.