Accessing Migrated Data Sets

Tectia Server for IBM z/OS can transfer files to and from cataloged, online DASD (direct access storage device) data sets. The following data set types are supported:

Tape Security

Tectia relies on the system security product for controlling access to data sets. Sites should ensure that the appropriate restrictions are in place for NL (No Label) or BLP (Bypass Label Processing). Refer to the RACF Security Administrator's Guide or appropriate documentation for your SAF for information on restricting access to resource ICHBLP in the FACILITY class, or equivalent functionality. Tectia does not read labels and does not have any label exits.

Operational Security and Tectia Controls

Using an offline tape data set requires that a tape drive is available and that the tape cassette is mounted on the drive. The operator must mount the drive or cancel the mount request. Outstanding mount requests can cause shortages, locking and deadlocks in resource handling in the system.

Using data sets on offline DASD volumes requires that the operator varies the volume device online. This requires the operator to decide whether the device can be varied online (it is probably offline for a good reason) and to enter the vary command or cancel the request.

Using a migrated data set requires the system to recall the data set to a user-accessible (level 0) volume before it can be read or overwritten. If the data set is on a migration level 1 (DASD) or migration level 2 (tape) volume, it is first copied to level 0.

The z/OS system operators must monitor mount requests to make sure they do not go unanswered or cause problems. They must also monitor the system for Tectia SFT Server processes and Tectia file transfer clients that are hanging on allocation requests for offline data sets.

In Tectia Server for IBM z/OS, mounting an offline data set is by default not allowed and recalling a migrated data set is by default allowed.

The Tectia end user controls mounting and recalling with the extended file attributes automount and autorecall. The user must set automount to yes or immed for Tectia to attempt to mount offline data sets. The user can set autorecall to no to avoid recalling a data set by mistake.

In addition, the administrator must set up access rights to the RACF facility SSZ.MOUNT for the users who will be mounting offline data sets with Tectia client tools for z/OS. For more information, see Tectia Server for IBM z/OS Administrator Manual.

Using Uncataloged Data Sets

Existing data sets that do not have entries in the catalog can be accessed by specifying a volume serial number and unit.

Example 1. Read a tape data set that has the data set name SRVACC1.SPECS.PDF and is the third data set on volume 456123.

Specify the file transfer attributes (UNIT, VOLUMES, DATASET_SEQUENCE_NUMBER) using a file transfer advice string:

sftp> sget /ftadv:un=TAPE,vol=456123,seqnum=3///'SRVACC1.SPECS.PDF' \ 

Alternatively, you can use the sftpg3 site command:

sftp> site unit=TAPE,volumes=456123,dataset_sequence_number=3
sftp> sget //'SRVACC1.SPECS.PDF' /home/clusr1/tmp/specs.pdf

Example 2. Create a data set without cataloging it using the NORMDISP attribute.

Specify the file transfer attributes (UNIT, NORMDISP) using a file transfer advice string:

sftp> sput /home/clusr1/tmp/specs-v2.pdf \ 

Alternatively, you can use the sftpg3 site command:

sftp> site unit=TAPE,normdisp=KEEP
sftp> sput /home/clusr1/tmp/specs-v2.pdf //'SRVACC1.SPECS.V2.PDF'

The DATACLAS, STORCLAS, and MGMTCLAS attributes are also available.

Requesting the System to Mount a Volume

For Tectia to request the system to mount an offline volume, you must use the AUTOMOUNT attribute. You must also have READ access to SSZ.MOUNT. For example, to read a data set on a tape volume, assuming that the data set has a catalog entry, use the following commands.

Specify the attribute with a file transfer advice string:

sftp> sget /ftadv:automount=yes///'SRVACC1.SPECS.PDF' \ 

Alternatively, you can use the sftpg3 site command:

sftp> site automount=yes
sftp> sget //'SRVACC1.SPECS.PDF' /home/clusr1/tmp/specs.pdf

When automount=yes, Tectia first attempts to allocate the data set without allowing the system to mount the data set if it is offline. If this allocation fails, Tectia retries the allocation with the mount request. You can make Tectia omit the first attempt by specifying automount=immed.

Low-Level Access

Tectia has a facility for low-level access to dynamic file allocation because of the large number of attributes that can be specified when allocating tape data sets.

Tectia allocates data sets by calling the SVC 99 interface. This interface has a table of text units. Each text unit consists of key, parameter count, and parameters. The parameters have a length field and data. The interface is documented in the Authorized Assembler Services Guide.

Tectia allocates files at the start of a file transfer (except if the file is already allocated and is represented by a DD name). Tectia sets text units based on the extended attributes. The FTADV/site parameter SVC99_TEXT_UNITS allows the user to add and change text units in the table. The value of svc99_text_units is a sequence of text units delimited by underscores ('_'). Each text unit has the format xxxxFvalues, where xxxx is the key in hexadecimal, F is a format character and values is a character string. The values part is empty or consists of one string or of several strings delimited by plus signs ('+'). No value may contain spaces, tabs, newlines or any of the characters '_+,/\'. The values part must not exceed 80 characters in length.

The format character indicates how the value(s) are encoded. The possible values are:

  • S: character string

  • X: hexadecimal

  • F: decimal number with length 4 in the text unit

  • H: decimal number with length 2 in the text unit

  • C: decimal number with length 1 in the text unit

  • -: no text unit

When the format character is '-', Tectia removes the text unit with the given key if it is in the table. For the other characters, Tectia replaces the value in the text unit with the given key or adds a new text unit.

The following attributes show how to encode some of the examples in the Authorized Assembler Services Guide. The attributes are not intended to be practical cases.

To specify an accessibility code of Z for an ANSI tape data set:

  • Using a file transfer advice string:

    sftp> cd /ftadv:svc99_text_units=8001XE9/
  • Using the site command:

    sftp> site svc99_text_units=8001XE9

To specify a RACF profile that was defined generically and request unallocation when a DCB is closed:

  • Using a file transfer advice string:

    sftp> cd /ftadv:svc99_text_units=800EXD9D7D9D6C6+80_001CX/
  • Using the site command:

    sftp> site svc99_text_units=800EXD9D7D9D6C6+80_001CX

To enter a Key Encode Specification and a Key Label:

  • Using a file transfer advice string:

    sftp> cd /ftadv:svc99_text_units=8026SH_8024SLABELQ1.LABELQ2.LABELQ3/
  • Using the site command:

    sftp> site svc99_text_units=8026SH_8024SLABELQ1.LABELQ2.LABELQ3