The Create Virtual Tape tool provides a simple interface for
creating, displaying, and deleting a virtual tape structure. The
intent of the CRTVTP tool is that you would create or replace a
virtual tape structure each time you need to use a virtual tape
function and replace or delete it after the tape media is written.
The system virtual tape support uses:
- A virtual tape resource - a hardware resource
- A virtual tape device - must be 'varied on'
- An IFS directory - will contain the saved data in a STMF
- An image catalog - must be kept in a 'ready' status
- An image catalog entry - must be in a 'mounted' status
Any SAVxxx command including SAVLIB(*NONSYS) may be used to save to
virtual tape. The data is saved to the IFS. Since media is not
involved during the save, an unattended save can occur.
The system DUPTAP command is used to copy from the virtual tape to
actual media.
Virtual tape can be used with the SAVSYSBCH TAA Tool. Thus you can
back up the entire system in an unattended manner from a batch job
which can be scheduled for a specific time.
To use the system support directly, you must be familiar with the
concepts and functions.
The CRTVTP TAA tool allows a simple approach where the user does not
directly use most of the functions. CRTVTP is intended to create a
virtual tape structure. After creating a structure, you would do the
following:
SAVxxx
DUPTAP
RPLVTP
An alternative is to also use RPLVTP command when the process begins.
This ensures that the device is varied on, the image catalog is in a
'ready' state and the required storage is at a minimum. Each use
would then be:
RPLVTP
SAVxxx
DUPTAP
RPLVTP
The overhead to do RPLVTP is fairly minimal. If you use the RPLVTP
approach, the basic structure will remain using about 300K (most of
this is caused by the minimum amount of an image catalog).
If you need to review and control the status, the TAA WRKVTP command
provides a work display with a variety of options and functions.
You must be authorized to the TAAVTP and TAACVTIFS Authorization
lists to use most of the supplied commands:
** CRTVTP. Creates a virtual tape structure.
** DLTVTP. Deletes a virtual tape structure. Only a virtual
tape structure created by CRTVTP may be deleted.
** DSPVTP. Displays the virtual tape devices and the available
virtual tape resources.
** RDYVTP. Ensures the image catalogs created by CRTVTP are in a
'ready' status and the corresponding devices are 'varied on'.
** RPLVTP. Replaces the structure built by CRTVTP to its
original values.
** WRKVTP. Provides a work display to allow review and control
of any virtual tape structures created by CRTVTP.
** CRTVTPRSC. Creates or describes a virtual tape resource to be
used.
System virtual tape advantages and support
------------------------------------------
The system virtual tape support allows an online save from any SAVxxx
command to a stream file in the IFS. Multiple libraries may be saved
to the same virtual tape device with a single command including
SAVLIB LIB(*NONSYS). When multiple libraries are saved on a single
command, the system overlaps the allocation and deallocation of
resources. This differs from *SAVF objects which allow only a single
library per save file object and no overlap of allocation occurs.
The virtual tape save function can occur unattended. The writing to
offline media occurs by using the DUPTAP command which copies from
the virtual tape device data to an actual tape device.
The system support requires the use of a tape device description
which is defined with a resource name of *VRT for virtual. A virtual
tape resource must be named or be created. An image catalog must be
created along with an entry describing the volume to be saved to.
To use the function at the system level, you must be familiar with
several concepts and details.
Basics of virtual tape resources
--------------------------------
A virtual tape device must refer to a virtual tape resource.
A virtual tape resource is not an object type on the system, but
rather a hardware resource. There are no system commands to directly
create or delete a virtual tape resource.
A virtual tape resource is automatically created by the system
CRTDEVTAP command using RSRCNAME(*VRT) when no available resources
exist. The names TAPVRT01-TAPVRT9999 are used, but only 35 may exist
at one time. The system solution has a tendency to create excess
resources rather than use an existing resource. An existing resource
will only be used if it is in a 'Not detected' status. This
overlooks the 'Operational' status which means a resource is not tied
to an existing device. The status conditions are described in
further detail later.
Multiple tape device descriptions may refer to the same virtual tape
resource, but only one such device description may be varied on at a
time.
Virtual tape resources require only a small amount of storage so the
space requirement is rarely a consideration.
Once created, a virtual tape resource can only be deleted by using
the DST service tools at IPL or SST. Its best to avoid doing this.
Getting started
---------------
** The TAA command WRKVTP provides a type of 'one stop shopping'
to review and control virtual tape. You should become
familiar with the command and its options. You must have *USE
authority to the TAAVTP and TAACVTIFS authorization lists to
use WRKVTP as well as the other TAA commands included in the
CRTVTP tool.
WRKVTP has no parameters and would be entered as:
WRKVTP
** If no virtual tape devices exist, the error messages describe
that you should use F8 to see a list of available tape
resources. If no tape resource exist, you will receive a
prompt that allows you to create 10. This should be
sufficient for most usage.
The Available Tape Resource display describes any resources
that are in a 'Not detected' or 'Operational' status.
The 'Not detected' status indicates that the resource reported
in at a previous IPL, but is not in use now. This is the
normal status for a resource that has not been in use to a
virtual tape device since the last IPL.
The 'Operational' status indicates that the resource has been
in use since the last IPL, but is not currently in use. This
would occur if you just created the resource or if you used
the resource with CRTVTP and then used DLTVTP for the same
virtual device.
In order to create a virtual tape device using CRTVTP, you
must know the name of a virtual tape resource that is
available.
-- If the Available Tape Resources display describes one
or more tape resources, you can position the cursor to
one and use F19. This will end the display, and the
tape resource you selected will appear at the top of
the WRKVTP display (upper right hand corner) and is
ready for use with CRTVTP.
-- If you do not have any virtual tape resources, return
to the WRKVTP display and use F9. If virtual tape
resources already exist in the 'Not detected' state,
the first of those resources will be returned.
Otherwise, this will cause a virtual tape resource to
be created. and the completion message will describe
the resource name that was created. The name of the
resource will also appear at the top of the display
(upper right hand corner) and is ready for use with
CRTVTP. Note that when F9 creates a resource it
immediately places it in Operational status, meaning
the resource is in use, or is planned to be in use.
** Before creating a virtual tape device, you must understand the
CRTVTP DENSITY parameter.
You must ensure that the density (the tape block size) that
will eventually be written to tape using DUPTAP is
synchronized with what is specified on CRTVTP (this value is
passed thru to the image catalog entry). To understand the
value to be specified, you must know the block size that is
written by a SAVxxx command using USEOPTBLK(*YES).
Use F6 from WRKVTP to prompt for the CRTVTP command and review
the help text for the DENSITY parameter (or the later
discussion of the command parameter).
The DUPTAP TODENSITY parameter should normally have this same
value. See the later section on 'DUPTAP command'.
If you have a single or identical tape devices on your system,
you can set a system wide default with the Application Value
CRTVTP in TAASECURE. Use EDTAPPVAL TAASECURE/CRTVTP to set
your default. This will allow the CRTVTP command to assume
the system wide default.
** You are now ready to create a virtual tape device. The name
VRT01 will be used in the following examples.
From the WRKVTP display, use F6 to prompt for CRTVTP.
Enter the values as:
VRTTAP(VRT01)
DENSITY - If you used EDTAPPVAL as described previously,
you should see the assigned value.
If not, enter a *VRTnnnK value.
RSRCNAME(TAPVRTnn)
Assuming you had selected a resource, the name you selected
would appear in the RSRCNAME parameter as the default.
You should see the TEXT parameter as 'Created by TAA CRTVTP on
xx/xx/xx'. This value is filled in from the prompt override
program.
Take the defaults for the other parameters which include:
-- An option exists to place the data in an IASP. See the
ASP parameter.
-- An option to describe the maximum storage that will be
allowed. See the later discussion.
-- The AUT parameter controls access to the Virtual Device
and Image Catalog. The default is *EXCLUDE. This will
prevent any user from saving to the virtual device
unless specifically authorized.
-- The DIRAUT parameter controls access to the IFS
Directory that will be created. It defaults to
*EXCLUDE. This prevents a user from using WRKLNK to
access or work with the IFS object.
-- The key feature of controlling security for Virtual
Tape is authorization to the Virtual Tape Device
descriptions. Only those users you want to be able to
use Virtual Tape should be authorized to the Virtual
Tape Device descriptions. See the later discussion of
'Virtual Tape Device Authorization'.
After Enter is pressed, the WRKVTP display will be refreshed
so you should see the device you created.
You should see that the device is 'varied on'. In order to
save to a virtual tape device, the device must be 'varied on'.
CRTVTP creates and 'varies on' the device. The device is also
specified to 'vary on' at IPL.
The status of the Image Catalog is shown. It must be in a
'ready' status to allow a save.
A size is shown from the size of the *STMF in the IFS. Before
any data is saved to the virtual tape, there is a default size
(varies per release).
** You are now ready to save to the virtual tape device. End the
WRKVTP display and return to command entry. Choose a small
library and enter:
SAVLIB LIB(xxx) DEV(VRT01)
** Use WRKVTP to review the status.
WRKVTP
You should see the size has increased and will be somewhat
larger than the size of the library that was saved.
** Use WRKVTP Option 7 (TAA DSPTAPLBL) to review the tape label
information. It will describe the date the first label (if
any) was written or if any files exist.
** Use WRKVTP Option 8 (TAA DSPSAVTAP) to see the objects that
were saved.
** To write from the virtual tape device to an actual tape
device, mount a tape and use DUPTAP such as:
DUPTAP FROMDEV(VRT01) TODEV(xxx) CHECK(*xxx)
TOENDOPT(*REWIND) TODENSITY(*VRTnnnK)
A CHECK(*NO) value allows you to write over the first active
file on the media. Note that the TOENDOPT parameter defaults
to *UNLOAD, but for the test, use *REWIND. The TODENSITY
value should agree with what was specified on CRTVTP (see the
section on DUPTAP).
** You can use DSPSAVTAP to review what has been written to the
tape. Specify the actual tape device:
DSPSAVTAP DEV(xxx)
You should see the same information that you saw with Option 8
from the WRKVTP display of the virtual tape device.
** An IPL will reset the image catalog to a 'not ready' status.
The device is created with ONLINE(*YES) so it is normally not
necessary to vary on the device.
You can simulate the status of an image catalog after an IPL
by unloading the image catalog. Return to command entry and
enter:
LODIMGCLG IMGCLG(VRT01) DEV(VRT01) OPTION(*UNLOAD)
Then enter WRKVTP again. You should see that the status is
now '*NOTRDY'.
A simple TAA command (RDYVTP) exists to ensure the device and
image catalog are in the proper status. Use F7 (RDYVTP) and
check the results.
The RDYVTP command finds all image catalogs created by CRTVTP
and ensures they are in a 'ready' status. The corresponding
devices are ensured to be 'varied on'.
** CRTVTP creates an image catalog of the same name as the the
virtual device. Image catalogs are always created in QUSRSYS.
You can review the image catalog by using Option 6 (WRKIMGCLG
system command).
** Use Option 12 from the WRKIMGCLG display to see the image
catalog entries associated with the image catalog that was
created (this could also be accessed directly with the
WRKIMGCLGE command).
** You should see that there is only one entry and it is in a
'mounted' status. This is the required status to perform a
save or DUPTAP operation. If you review the 'help
information' for the status field, you can see that this is
the actual status only if the image catalog is in a 'ready'
status. Keeping the image catalog in a 'ready' status would
not be necessary if you begin each save function with RPLVTP
or RDYVTP.
The other status value you may see for an image catalog entry
is 'loaded' which means the entry is available to be mounted.
An analogy is to consider the image catalog as a CD player
with several slots for CDs that can be 'loaded', but only one
can be played at a time. The one you want to play must be in
a 'mounted' status. There can only be one in a 'mounted'
status. The 'mounted' status is required to use a SAVxxx
command or the DUPTAP command.
Each entry represents one volume that was saved to. You
should see the name VOL001. If a save operation exceeded the
maximum size, an additional volume would be automatically
created with a large maximum size. Generating an additional
volume complicates the use of DUPTAP (see the later
discussion) and therefore the maximum size (MAXSTG parameter)
specified on CRTVTP should be a large value. The default is
to assign a value of 50% of the unused space in ASP 1. If an
IASP is described, it is the unused space in ASP 1 of the
IASP.
Use F11 from the Work Image Catalog Entries display to see
size information. Unlike WRKVTP, only the maximum size and a
percentage are shown. You have to perform a multiplication to
determine the size in MB. Performing a multiplication will
not necessarily provide an accurate value because the minimum
percentage is 0.1 of the maximum size. If you saved a large
amount of data, the multiplication will provide a reasonable
value.
The size shown on WRKVTP comes from the size of the *STMF
associated with the virtual devices.
** Use WRKLNK to review the root as:
WRKLNK /
Use Option 5 to see the directories. Rollup until you see the
TAAVTP directory. This is created automatically on the first
use of CRTVTP.
Use Option 5 for the TAAVTP directory to see the
subdirectories of TAAVTP. You should see a sub-directory for
the name of your virtual tape device VRT01.
Use Option 5 for the VRT01 sub-directory to see the STMF which
has a name of VOL001.
Use Option 8 for the VOL001 stream file to review the
attributes which includes the actual size (rollup to page 2)
in the IFS.
** Return to the WRKVTP display.
Enter Option 3 to replace a virtual tape structure. This will
delete the existing structure and re-create it. This causes
the size to be minimized and ensures the device is varied on
and the image catalog is in a 'ready' status.
** You may use Option 4 to delete a virtual tape structure.
However, once a structure is created, the simplest solution is
to use RPLVTP (Option 3). There is approximately 600K
required to have an empty virtual tape structure (most of this
is required for an empty image catalog).
Why replace the virtual tape structure after each usage
-------------------------------------------------------
The recommended approach avoids some pitfalls and tries to make it
very simple.
It is possible to re-use the structure you have created by doing
another save with CLEAR(*ALL) or INZTAP (or the TAA CLRTAP command).
However, you are exposed to the following:
** If you save a large amount of data, the allocated size is
fixed in the IFS. Writing a smaller amount of data or using a
function like INZTAP does not change the allocated size.
** If you re-IPL, the status of the image catalog goes to 'not
ready'. You must use RDYVTP or LODIMGCLG or the load option
on WRKIMGCLG to place it in a 'ready' status.
** Attempting to fully understand the intricacies of the system
support when something is in error is non-trivial. You can
spend a good deal of time attempting to understand how it
works and it is not easy to remember.
SAVxxx functions
----------------
As with saving directly to media, you may have multiple SAVxxx
commands and add data to the same virtual tape device. The SEQNBR
parameter defaults to *END.
Avoid specifying DTACPR(*YES) when saving to a virtual tape device.
The SAV command may be used to save from the IFS. The DEV parameter
would be entered as:
SAV DEV('/qsys.lib/vrt01.devd') OBJ(xxx)
Typical CRTVTP approach
-----------------------
The TAA solution avoids the complexities of the system solution. The
intent is you would create a virtual tape structure, perform the
save, do DUPTAP to offload the data, and then replace the virtual
tape structure with RPLVTP. With this approach, you do not have to
concern yourself with the complexities of the system approach.
A typical approach would be two CL programs. You must first use the
CRTVTP function to create a virtual tape structure. The first
program would contain:
RPLVTP VRTTAP(VRT01)
SAVLIB LIB(xxx ...) DEV(VRT01) ...
CHKSAVRST ERRORSONLY(*YES)
And a second program for:
DUPTAP FROMDEV(VRT01) TODEV(xxx)
CHECK(*xxx) TODENSITY(*VRTnnnK)
RPLVTP VRTTAP(VRT01)
While there is some overhead in using RPLVTP, it avoids the
complexities and keeps your online storage at a minimal amount.
If you don't mind the amount of storage required for a save existing
on your system and use CLEAR(*ALL) on the SAV command, you could
replace the first RPLVTP command with RDYVTP which will cause less
overhead. RDYVTP ensures the structure is ready to be used.
If you wanted to do the whole function unattended at a specific time,
you could mount a tape and combine the above functions into a single
program.
** The RPLVTP command deletes the existing structure and
re-creates it using an internal CRTVTP. This does the
following:
-- Creates the device and varies it on.
-- Creates an image catalog in QUSRSYS by the same name as
the virtual tape device.
-- Creates the /TAAVTP directory if it does not exist.
The *PUBLIC user is given all rights.
-- Creates a sub directory using the VRT01 name in the
'/TAAVTP' directory. The *PUBLIC user is given all
rights.
-- Adds an image catalog entry with a default size. The
CRTVTP MAXSTG parameter allows you to specify a value,
but defaults to *DFT which means 50% of the unused
storage in the system ASP. This is not the allocated
size, but rather the size used by the system to
determine when to start another virtual tape volume.
The simplest solution is to allow a sufficient size to
avoid having the system generate another virtual tape
volume.
If the amount saved overflows the size specified, it
takes multiple DUPTAP commands to output to media. See
the later section on the 'DUPTAP' command.
-- Loads the image catalog entry.
** The SAVLIB command does a normal save of one or more libraries
to the virtual tape device. You should not specify
DTACPR(*YES) as this has an adverse affect on save time. The
data is placed in the '/TAAVTP/VRT01' directory in the IFS. A
stream file is created.
** The TAA CHKSAVRST command nets out the job log information
relative to the save. This allows you to easily determine any
errors that may have occurred.
** The DUPTAP command copies the saved data to a specified tape
device. You will need to specify CHECK(*NO) if there is an
active file on the tape and you want to write over the first
file. You will need to ensure that the TODENSITY parameter is
the same as that specified on CRTVTP or can be used. See the
section on the 'DUPTAP command'.
** The RPLVTP command recreates the structure and minimizes the
amount of online storage.
DUPTAP command
--------------
The system DUPTAP command is used to write from an image catalog
entry to offline media. Assume you used CRTVTP to create the VRT01
tape device and did a save operation to VRT01.
A simple DUPTAP command would be:
DUPTAP FROMDEV(VRT01) TODEV(TAP01) CHECK(*NO)
TODENSITY(*VRTnnnK)
This would copy the data from the image catalog entry to the TAP01
device. The CHECK(*NO) entry would allow you to write over an active
volume.
The DUPTAP command allows identifying the volume identifier which
would be needed if more than one catalog entry exists.
DUPTAP also allows a TODENSITY parameter which can be defaulted in
some cases. The value should normally be consistent with what was
used on CRTVTP.
Some density differences are valid, but the rules vary per device
type and media type. If you use different densities between the
CRTVTP command and the DUPTAP command, be sure to test a sample
restore.
Use F10 to see the additional parameters on DUPTAP.
If you specified a MAXSTG size of 20 GB, saved 15 GB and a single
media only holds 10 GB, DUPTAP will prompt for another tape mount
when needed. Restore operations will work normally from the multiple
volumes.
If you specified a MAXSTG size of 1GB and saved more than 1GB, an
additional volume would be created in the image catalog. The
additional volume added would have a large maximum size. DUPTAP will
only write one volume per use of the command. You will need the
WRKIMGCLGE command to review the volume names generated by the system
which must be specified on DUPTAP.
Use of other tape commands
--------------------------
After a save command occurs, you can review the data with the DSPTAP
command or for a more convenient use, the DSPSAVTAP TAA command.
INZTAP may be used or the TAA CLRTAP command. These commands do not
reset the allocated size in the IFS. The allocated size can be reset
using the CHGIMGCLGE command with ALCSTG(*MIN).
However, for the simplest use, the RPLVTP command avoids confusion.
DUPTAP may be used to duplicate from one virtual tape device to
another.
Other TAA Tools that operate on tape devices may also be used such
as:
CVTDSPTAP
CVTTAPSAVD
DSPTAPLBL
RTVTAPID
RTVTAPLBL
DSPVTP data area
-----------------
The DSPVTP command supports the DTAARA parameter which allows an
option on the DSPVTP to output the TAAVTP data area in QTEMP. The
data area will contain a list of the available virtual tape resources
as seen on the listing (this is the same information as seen from the
WRKVTP F8 option for Available Resources).
You can access the first name in the list with the command:
RTVDTAARA DTAARA(QTEMP/TAAVTP (1 10))
RTNVAR(&xxx)
Or a program could walk thru the list to see if a specific resource
is available.
Automating the CRTVTP command
-----------------------------
CRTVTP requires that the virtual tape resource that will be used is
specified for the RSRCNAME parameter.
A simple solution is to create a sufficient number of virtual tape
resources so you can assign them to specific functions. For example,
the VRT05 tape device could always be used with the TAPVRT05 virtual
tape resource.
It is possible to write a CL program that will allow the resource
name to be a variable by using the DTAARA option on DSPVTP. This
creates the TAAVTP data area in QTEMP which contains the list of
available resources. Assuming you have some available virtual tape
resources, you can access the data area and use the first name.
Note that DSPVTP is preferred over CRTVTPRSC because CRTVTPRSC will
add a new resource if no virtual tape resources are in the 'Not
detected' state. In general, you should prevent creating too many
resources.
The CL code could look as follows:
DCL &DTAARA *CHAR LEN(2000)
DCL &RSRCNAME *CHAR LEN(10)
DSPVTP DTAARA(*YES) OUTPUT(*PRINT)
DLTSPLF FILE(VRTTAP) SPLNBR(*LAST)
RTVDTAARA DTAARA(QTEMP/TAAVTP) RTNVAR(&DTAARA)
CHGVAR &RSRCNAME %SST(&DTAARA 1 10)
IF (&RSRCNAME *EQ ' ') DO
.
. /* Your handling of none available */
.
ENDDO
CRTVTP VRTTAP(VRTnn) DENSITY(*VRTnnnK) +
RSRCNAME(&RSRCNAME)
Virtual Tape Device Authorization
----------------------------------
The important security aspect of using Virtual Tape is who is
authorized use to a Virtual Tape Device.
By default, a Virtual Device created by CRTVTP is *PUBLIC *EXCLUDE.
Any user who has *USE authority to a virtual device is allowed to
perform a SAVxxx command (as per the restrictions of the SAVxxx
command) and use DUPTAP. For example, if the user has the special
authority *SAVSYS, any SAV command may be used on any object.
Without SAVSYS, the user must have *OBJEXIST authority to the objects
to be saved.
Even though the user may not be authorized to the Image Catalog or
the IFS Directory, SAVxxx and DUPTAP may still be used.
CRTVTP Tool Authorization
--------------------------
Any user with *USE authority to the TAAVTP and TAACVTIFS
Authorization Lists may use CRTVTP, DLTVTP, DSPVTP, RPLVTP, RDYVTP,
WRKVTP, or CRTVTPRSC.
The following programs adopt the QSECOFR user profile, but ensure
that the user is authorized to the TAAVTP and TAACVTIFS authorization
lists as required:
TAATAPNC Create Virtual Tape
TAATAPNC2 Delete Virtual Tape
TAATAPNC4 Display Virtual Tape
TAATAPNC6 Ready Virtual Tape
TAATAPNC7 Work Virtual Tape
TAATAPNC11 Sub program for IFS functions
DLTVTP, RPLVTP, and the various WRKVTP functions will only operate on
a virtual tape structure created by CRTVTP. A user must have *ALL
authority to the device description and the image catalog to delete
or replace a virtual tape structure.
Any directories created are set according to the DIRAUT parameter on
CRTVTP which defaults to *PUBLIC DTAAUT(*EXCLUDE). OBJAUT(*NONE) is
specified. During the running of WRKVTP and DSPVTP, the TAA
SWPUSRPRF (Swap User Profile) command is used to swap to the QSECOFR
user profile which ensures that any user authorized to the TAACVTIFS
and TAAVTP authorization lists will have access to the IFS objects.
This performs as an adopted program for IFS functions.
Using SWPUSRPRF in a save operation
-----------------------------------
A user with only *SAVSYS authority will not be able to save to
Virtual Tape unless he is authorized for *RWX for the directories and
stream files. You may set the *PUBLIC user to these rights or use
the SWPUSRPRF technique.
Because program adopt does not allow adoption to the IFS, the
SWPUSRPRF command may be used during a save to cause the same
function. SWPUSRPRF should exist in a program that adopts the
QSECOFR profile and is authorized to those users you want to be able
to perform a specific save operation.
You must build up the command in a variable such as:
DCL &CMD *CHAR LEN(5000)
.
CHGVAR &CMD ('SAVLIB LIB(LIB1 LIB2) +
DEV(VRT01) ...')
SWPUSRPRF USRPRF(QSECOFR) CMD(&CMD)
Permanent virtual tape devices
------------------------------
The recommended approach with the CRTVTP tool is to replace the
virtual tape structure after the SAVxxx data has been written to tape
with DUPTAP.
This is not a requirement, but is the simplest approach to avoid
confusion and ensure that the space required for the save data is
cleaned up.
You could have multiple virtual tape structures for different save
requirements.
It is possible to have permanent virtual tape structures in existence
that may be re-used. However, you must become familiar with keeping
the image catalog 'ready' and the image catalog entry 'mounted'. See
the next section on 'Additional virtual tape resources'.
Additional virtual tape resources
---------------------------------
There are several reasons why you may want to have more than a single
virtual tape structure such as:
** Concurrent saves will be used.
** Multiple saves will occur before any use of DUPTAP.
** Individuals may want their own virtual tape structure and
determine when a SAVxxx should be run for their objects.
You may need a unique virtual tape device and a unique virtual tape
resource for each situation.
Use the WRKVTP command with Option 8 to review what virtual tape
resources exist. If you need additional virtual tape resources, use
the WRKVTP F9 option (TAA CRTVTPRSC command) as described previously.
If a new resource is not created, you may have to create a sufficient
number of virtual tape devices with CRTVTP so that all the available
virtual tape resources are used. Then CRTVTPRSC can be used to add a
new resource. The completion message will describe if an existing
virtual tape resource name should be used or a new resource was
created.
Performance considerations
--------------------------
Avoid specifying DTACPR(*YES) when saving to a virtual tape device.
Because a SAVxxx command to virtual tape is writing to disk (the IFS)
as opposed to tape, the number of disk arms is a performance
consideration. The more disk arms that exist, the faster the SAVxxx
will occur.
If you have few disk arms, you may find that using a SAVxxx command
directly to tape will provide better performance.
An option exists to place the data in an independent ASP. This has
the advantage of allowing you to dedicate a disk arm for the output.
Independent ASP Support
-----------------------
You may create a structure to place the IFS data on an independent
ASP by specifying a name on the ASP parameter of CRTVTP. Using an
independent ASP can be a significant performance advantage.
When using one of the xxxVTP supplied commands, you must ensure that
the independent ASP is varied on. The SAVxxx and DUPTAP commands
have the same requirement.
WRKVTP is tolerant of an ASP that does not exist or is not varied on,
but the full information cannot be provided. The ASP name will
appear in reverse image if not varied on.
Contrast with other TAA Tools
-----------------------------
** The SAVLIBSAVF (Save Library to Save File) tool saves one or
more libraries to save files in a specified library. There is
very little conceptual difference between SAVLIBSAVF and the
system virtual tape support. SAVLIBSAVF saves to *SAVF
objects as opposed to a stream file. After saving to offline
media with a normal SAVxxx command, the DLTLIBSAVF command
deletes the save files or you may clear the library.
Significant differences exist with the virtual tape support:
-- SAVLIBSAVF cannot be used for LIB(*NONSYS).
LIB(*ALLUSR) is supported.
-- Saving to a list of save files does not allow overlap
of allocation and deallocation.
-- SAVLIBSAVF does not support saving IFS objects.
However, before saving the library to offline media,
you could use the SAV command to save to a save file in
the backup library.
-- When the backup library is saved to offline media, save
files are saved rather than individual objects. To
recover, you would restore one or more save files and
then use normal RST commands from the online save
files. If you rarely use a RSTxxx command for
recovery, this can be a could tradeoff.
SAVLIBSAVF defaults to DTACPR(*YES) which significantly
reduces the size required, but will require more CPU. This
may be a good tradeoff depending on your requirements.
** The SRCARC (Source Archive) tool is designed for source files
and allows multiple online versions per source member. The
UPDSRCARC command will add new versions to the source archive
based on the last change date of a source member. The SRCARC
tool can eliminate or minimize the need to restore source from
offline media.
** The SPLARC (Spool Archive) tool allows you to archive spooled
files. Each spooled file is converted to a data base member.
The spooled files are tracked both online and offline based on
specified retention days. Re-printing occurs easily if the
data base file containing the converted spooled file is
online.
** The DTAARC (Data Archive) tool allows you to create duplicate
files on line and have multiple versions. The tool is not
intended to replace normal saves, but rather to provide online
versions which can be reviewed without restoring from media.
A similar approach could be done with virtual tape, but you
would have to manage the versions.
CRTVTP escape messages you can monitor for
-------------------------------------------
None. Escape messages from based on functions will be re-sent.
DLTVTP escape messages you can monitor for
------------------------------------------
TAA9894 No device, image catalog, or directory exists
TAA9895 No device or image catalog exists.
A directory of the same name exists
Escape messages from based on functions will be re-sent.
DSPVTP escape messages you can monitor for
------------------------------------------
None. Escape messages from based on functions will be re-sent.
RDYVTP escape messages you can monitor for
------------------------------------------
TAA9891 Some failure occurred.
Escape messages from based on functions will be re-sent.
RPLVTP escape messages you can monitor for
------------------------------------------
None. Escape messages from based on functions will be re-sent.
CRTVTPRSC escape messages you can monitor for
---------------------------------------------
None. Escape messages from based on functions will be re-sent.
CRTVTP command parameters *CMD
-------------------------
VRTTAP The name of the virtual tape device and image
catalog to be created.
A directory of the same name will be created. If
ASP(*SYSBAS) is used, the /TAAVTP directory will be
created if it does not already exist. A
sub-directory /TAAVTP/xxxxx will also be created
where xxxxx is the VRTTAP value.
If an ASP name is entered, the /TAAVTP directory and
sub-directory will be created in the directory with
the same name as the independent ASP. The ASP must
be varied on to perform any of the xxxVTP commands.
DENSITY The density (optimum block size) of the tape blocks
to be used.
The default is *DFT which is valid if you have
entered a system wide default using EDTAPPVAL
TAASECURE/CRTVTP.
The valid size values are *VRT256K, *VRT240K,
*VRT64K, or *VRT32K.
If a *VRTnnnK density is specified, it should agree
with the block size that is written by a SAVxxx
command when USEOPTBLK(*YES) is specified. If you
don't know the size, mount one of your SAVxxx
USEOPTBLK(*YES) written tapes and specify:
DSPTAP DEV(xxx) DATA(*LABELS)
The 'Block length' description contains the block
size in bytes which is the optimum block size used
by the save.
The following chart should assist you in entering
the density parameter.
Block length DENSITY
in bytes Parameter
------------ ---------
262144 *VRT256K
245769 *VRT240K
65536 *VRT64K
32768 *VRT32K
The special value *TAPDEV may be entered which
requires a tape device to be named for the TAPDEV
parameter. Specifying the tape device name allows
CRTVTP to determine the optimum block size to be
used. For example, if the tape device is a 6384,
the optimum block size is *VRT256K and will always
be used.
However, for some device types, the optimum block
size used is determined by the media type that is
mounted when the tape is actually written. Since
the tape media is normally not mounted when a save
occurs to virtual tape, you must know the optimum
block size ahead of time. If you are not sure, use
DSPTAP as described previously and specify a
*VRTnnnK value.
If *TAPDEV is specified, an informational message is
sent describing the *VRTnnnK value that will be
used. This should normally agree with the optimum
block size of the block length of your save tape and
the TODENSITY parameter on DUPTAP. Some differences
are valid, but be sure to check a sample restore.
TAPDEV The tape device to be used to determine the optimum
block size. The default is *NONE meaning the value
specified for the DENSITY parameter will be used.
If DENSITY(*TAPDEV) is specified, you must specify a
valid tape device name. This allows CRTVTP to
determine the optimum block density value. See the
previous comments for the DENSITY parameter for
whether you can use a device name.
Some devices like 3490 support two different media
sizes and you must specify a *VRTnnnK value for the
DENSITY parameter.
RSRCNAME The virtual tape resource name.
TAPVRTNN is the default when entered as
A specific TAAVRTnn name must be entered for an
existing available virtual tape resource. Use
DSPVTP to determine any available virtual tape
resources that can be used. Any resource in the
section 'Available Virtual Tape Resources' may be
used. If none exist, use CRTVTPRSC to add a virtual
tape resource. The system assigns names
TAPVRT01-TAPVRT9999 when a new resource is created,
but only 35 may exist at a time.
MAXSTG The maximum storage in GB. The default is *DFT
which means 50% of the unused space in ASP 1. This
is not the allocated size, but rather the size used
by the system support to determine when to start
another virtual tape volume.
If the size specified is not sufficient to hold the
data to be saved, the system automatically creates
another volume in the image catalog with a large
maximum size. This complicates the DUPTAP function
as you must do a unique DUPTAP command for each
volume.
The simplest solution is to allow a sufficient
maximum size to avoid having the system generate
another tape volume in the image catalog.
If there is only one volume in the image catalog,
but DUPTAP cannot write all of the saved data to a
single media volume, normal prompting will occur to
request mounting of additional media. Normal RST
commands can be used and will request mounting of
additional media.
The CRTVTP completion message will describe the
amount of storage specified for the volume. If it
is too low, use DLTVTP and re-enter CRTVTP with a
larger size.
ASP The ASP to place the data in. This entry determines
the directory that will be used.
The default is *SYSBAS which means ASP 1 of the
system ASP.
A specific independent ASP name may be entered.
TEXT The text description assigned to the tape device and
image catalog.
*DFT is the default. This will create a description
of 'Created by TAA CRTVTP on xx/xx/xx'. If command
prompting is used, the prompt override program will
supply this value for the text description.
A specific text description may be entered.
The value of the ASP parameter is stored in the last
10 bytes of the Image Catalog text description.
This data should be left as is to allow the DLTVTP
command to clean up the data and directory entry.
AUT The authority to the tape device description and the
image catalog.
*EXCLUDE is the default. Only those users you want
to be able to use a virtual tape device should have
*USE authority to the device description.
*CHANGE, *USE, or *ALL may be specified.
DIRAUT The authority to the IFS directory.
*EXCLUDE is the default.
*RWX, *RX, *RW, *WX, *R, *W, or *X may be specified.
DLTVTP command parameters *CMD
-------------------------
VRTTAP The name of the virtual tape device and image
catalog that was created by CRTVTP.
Only a virtual tape device that was created by
CRTVTP can be deleted. The user must have *ALL
authority to both the tape device and the image
catalog.
Both the virtual tape device and the image catalog
will be deleted along with the sub directory. The
TAAVTP directory and the virtual tape resource will
remain.
DSPVTP command parameters *CMD
-------------------------
DTAARA A *YES/*NO value for whether the list as shown for
the available virtual tape resources (those that are
not assigned to a virtual tape device) will be
output to the TAAVTP data area in QTEMP.
*NO is the default. No data area will be created.
*YES may be specified to create or change the TAAVTP
data area in QTEMP with the available virtual tape
resource names. Each name takes 10 bytes. The
remaining area will be blank. If no names are
available, the entire data area will be blank.
You can access the first name on the list with:
RTVDTAARA DTAARA(QTEMP/TAAVTP (1 10))
RTNVAR(&xxx)
OUTPUT How to output the results. * is the default to
display the VRTTAP spooled file if the command is
entered interactively. The spooled file is deleted
after it is displayed.
If the command is entered in batch or *PRINT is
specified, the spooled file is output and retained.
RDYVTP command parameters *CMD
-------------------------
IMGCLG The name of the image catalog that was created by
CRTVTP. The image catalog will be ensured to be in
a 'ready' status and the corresponding device is
'varied on'.
*ALL is the default for all image catalogs created
by CRTVTP.
A specific image catalog created by CRTVTP may be
specified.
RPLVTP command parameters *CMD
-------------------------
VRTTAP The name of the virtual tape device and image
catalog that was created by CRTVTP.
Only a virtual tape device that was created by
CRTVTP can be replaced. The user must have *ALL
authority to both the tape device and the image
catalog.
The current attributes are extracted and used to
re-create the structure. Both DLTVTP and CRTVTP are
used internally. If you have not changed the
attributes (eg with the CHGIMGCLGE command), the
structure will look the same as you created with
CRTVTP.
The authorizations are copied from the current tape
device and image catalog to the new objects.
WRKVTP command parameters *CMD
-------------------------
No parameters exist.
CRTVTPRSC command parameters *CMD
----------------------------
No parameters exist.
Restrictions
------------
You must have *USE authority to the TAAVTP and TAACVTIFS
Authorization Lists to use the commands.
Only a virtual tape structure created by CRTVTP may be deleted by
DLTVTP or replaced by RPLVTP.
The ASP parameter value specified on CRTVTP is placed in positions
41-50 of the image catalog text description. This value must be left
as is.
Prerequisites
-------------
The following TAA Tools must be on your system:
CHGOBJD2 Change object description 2
CHKIFSE Change IFS entry
CVTOBJD Convert object description
CVTIMGCLG Convert image catalog
CVTIMGCLGE Convert image catalog entries
DSPTAPLBL Display tape label
RSNLSTMSG Resend last message
RTVDEVTAP Retrieve device tape
RTVSPCAUT Retrieve special authority
RTVSYSVAL3 Retrieve system value 3
RTVTAPLBL Retrieve tape label
RTVVTPRSC Retrieve virtual tape resource
SNDCOMPMSG Send completion message
SNDDIAGMSG Send diagnostic message
SNDESCINF Send escape information
SNDESCMSG Send escape message
SNDLNGMSG Send long message
SWPUSRPRF Swap user profile
Implementation
--------------
None, the tool is ready to use.
Objects used by the tool
------------------------
Object Type Attribute Src member Src file
------ ---- --------- ---------- ----------
CRTVTP *CMD TAATAPN QATTCMD
DLTVTP *CMD TAATAPN2 QATTCMD
CRTVTPRSC *CMD TAATAPN3 QATTCMD
DSPVTP *CMD TAATAPN4 QATTCMD
RPLVTP *CMD TAATAPN5 QATTCMD
RDYVTP *CMD TAATAPN6 QATTCMD
WRKVTP *CMD TAATAPN7 QATTCMD
TAATAPNC *PGM CLP TAATAPNC QATTCL
TAATAPNC2 *PGM CLP TAATAPNC2 QATTCL
TAATAPNC3 *PGM CLP TAATAPNC3 QATTCL
TAATAPNC4 *PGM CLP TAATAPNC4 QATTCL
TAATAPNC5 *PGM CLP TAATAPNC5 QATTCL
TAATAPNC6 *PGM CLP TAATAPNC6 QATTCL
TAATAPNC7 *PGM CLP TAATAPNC7 QATTCL
TAATAPNC11 *PGM CLP TAATAPNC11 QATTCL
TAATAPNC14 *PGM CLP TAATAPNC14 QATTCL
TAATAPNC17 *PGM CLP TAATAPNC17 QATTCL
TAATAPNC18 *PGM CLP TAATAPNC18 QATTCL
TAATAPNR4 *PGM RPG TAATAPNR4 QATTRPG
TAATAPND *FILE DSPF TAATAPND QATTDDS
TAATAPNE *FILE DSPF TAATAPNE QATTDDS
The CRTVTP Application Value (*USRSPC) exists in TAASECURE.
Structure
---------
CRTVTP Cmd
TAATAPNC CL pgm
TAATAPNC11 CL pgm for prompt override
DLTVTP Cmd
TAATAPNC2 CL pgm
CRTVTPRSC Cmd
TAATAPNC3 CL pgm
DSPVTP Cmd
TAATAPNC4 CL pgm
TAATAPNR4 RPG pgm
TAATAPNC14 CL pgm
RPLVTP Cmd
TAATAPNC5 CL pgm
RDYVTP Cmd
TAATAPNC6 CL pgm
WRKVTP Cmd
TAATAPNC7 CL pgm
TAATAPNR7 RPG pgm
TAATAPNC14 CL pgm to access size
TAATAPND Dsp file
TAATAPNC17 Sub pgm for options and F keys
TAATAPNC18 Sub pgm for vary on of IASP
TAATAPNE Dsp file
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