This section provides information for the following device and system file related topics:
installing on fixed-block addressing (FBA) devices; and
defining new devices.
All device definitions for Adabas control statements for FBA disks should specify one of the following devices types:
FBA SCSI devices: Specify device types of 5512, 6512, or 7512.
Virtual FBA devices: Specify device types of 5121, 5122, or 5123.
Note:
Virtual FBA devices are not permanent and are, therefore, only
suitable for holding temporary or work data sets.
Choose a device type based on the block sizes given in the following tables:
| Dev Type | Asso blksz | Data blksz | Work blksz | Temp blksz | Sort blksz | PLOG blksz | CLOG blksz |
|---|---|---|---|---|---|---|---|
| 5512 | 2048 | 4096 | 4096 | 4096 | 4096 | 4096 | 4096 |
| 6512 | 4096 | 8192 | 8192 | 8192 | 8192 | 8192 | 8192 |
| 7512 | 4096 | 16384 | 16384 | 16384 | 16384 | 16384 | 16384 |
| Dev Type | Asso blksz | Data blksz | Work blksz | Temp blksz | Sort blksz | PLOG blksz | CLOG blksz |
|---|---|---|---|---|---|---|---|
| 5121 | 2048 | 4096 | 4096 | 4096 | 4096 | 4096 | 4096 |
| 5122 | 4096 | 8192 | 8192 | 8192 | 8192 | 8192 | 8192 |
| 5123 | 4096 | 16384 | 16384 | 16384 | 16384 | 16384 | 16384 |
The pseudo-cylinder for each of these devices has a different number of blocks as described below:
5512 cylinder = FBA blocks/1024 6512 cylinder = FBA blocks/1024 7512 cylinder = FBA blocks/1024 5121 cylinder = FBA blocks/960 5122 cylinder = FBA blocks/960 5123 cylinder = FBA blocks/960
The size definitions for FBA devices on Adabas control statements can specify the number of pseudo-cylinders or the number of Adabas blocks (RABNs).
Make sure that the number of FBA blocks in the minidisk is a multiple of the pseudo-cylinders listed above. In addition, the minidisk size must be one pseudo-cylinder larger than the size specified in the Adabas size definitions:
An SCSI pseudo-cylinder comprises 1,024 elements of 512 bytes each, or 512 K per pseudo-cylinder.
A virtual FBA pseudo-cylinder comprises 960 elements of 512 bytes each, or 480 K per pseudo-cylinder.
Support for new device types that include user-defined block sizes can be implemented in Adabas by modifying one of the table of device-constant entries (TDCEs) reserved for this purpose. A TDCE is X’40’ bytes long and the first free TDCE can be identified by X’0000’ in its first two bytes (TDCDT).
Under z/VM for all versions of Adabas prior to Version 6.2, the address of the first TDCE is at offset ADAIOR+ X‘34’.
For Adabas Version 6.2 and 7.1, TDCE entries are in the ADAIOR CSECT TDCON: the first TDCE entry is at offset 0; the first free TDCE entry is at offset X‘680’.
This information is valuable when adding an additional TDCE entry.
The ADDEVICE EXEC distributed on the release tape can be used to add new device types. This EXEC creates zap files called USERDEVn ZAP to modify the TDCEs. It also modifies the table of valid device names DEVICE TABLE and the USERDEV TABLE. These tables are used for verification during the online installation procedure.
The information in the following tables must be zapped into the first free TDCE. The rules described in the section General Rules for Defining Device Block Sizes must be followed when changing the TDCE.
| Label | Offset | Contents |
|---|---|---|
| TDCDT | 00 | Device type in unsigned decimal (X’3385’), must be numeric, and unique among all TDCEs |
| TDCKSN | 02 | Constant set number: must be uniquely chosen from the values X’28’ (reserved for BS2000 device type 2006), X’2B’, or X’2E’ |
| TDCF | 03 | The flag bit must be set—TDCFFBA (X’80’) for FBA/PAM devices or TDCFCKD (X’40’) for CKD devices |
| TDCDT1 | 04 | see note below |
| TDCDT2 | 05 | see note below |
| TDCDT3 | 06 | see note below |
| TDCDT4 | 07 | see note below |
| TDCMSBS | 08 | Refer to the TDCMSBS default table in appendix A in Maximum Sequential Block Size in the Adabas z/OS installation instructions for more system and device related information. |
| TDCTPC | 0A | Number of tracks per cylinder |
| TDCCIPT | 0C | Number of FBA blocks or PAM pages per track (if TDCFFBA is set). For BS2000 less than or equal to 16. |
| TDCBPCI | 0E | Number of bytes per FBA block or PAM page (2048 if TDCFFBA is set) |
| TDCABPT | 10 | Number of Associator blocks per track |
| TDCABS | 12 | Associator block size |
| TDCACPB | 14 | Number of FBA blocks or PAM pages per Associator block (if TDCFFBA is set) |
| TDCDBPT | 16 | Number of Data Storage blocks per track |
| TDCDBS | 18 | Data Storage block size |
| TDCDCPB | 1A | Number of FBA blocks or PAM pages per Data Storage block (if TDCFFBA is set) |
| TDCWBPT | 1C | Number of Work blocks per track |
| TDCWBS | 1E | Work block size |
| TDCWCPB | 20 | Number of FBA blocks or PAM pages per Work block (if TDCFFBA is set) |
| TDCTSBPT | 22 | Number of TEMP or SORT blocks per track (if TDCFFBA is set) |
| TDCTSBS | 24 | TEMP or SORT block size |
| TDCTSCPB | 26 | Number of FBA blocks or PAM pages per TEMP or SORT block (if TDCFFBA is set) |
| TDCPBPT | 28 | Number of PLOG blocks per track |
| TDCPBS | 2A | PLOG block size |
| TDCPCPB | 2C | Number of FBA blocks or PAM pages per PLOG block (if TDCFFBA is set) |
| TDCCBPT | 2E | Number of CLOG blocks per track |
| TDCCBS | 30 | CLOG block size |
| TDCCCPB | 32 | Number of FBA blocks or PAM pages per CLOG block (if TDCFFBA is set) |
Note:
One or more z/VM codes for identifying the device type: the UCB unit
type from UCBTBYT4.
In addition, the length of a sequential protection log block may have to be increased. Under z/VM, this length is contained in the corresponding PTT entry in CSECT I_PTT of the load module ADAIOR. PTT entries begin at offset 0 into CSECT I_PTT.
Each PTT entry is X’10’ bytes long and has the structure shown below:
| Label | Offset | Contents |
|---|---|---|
| PTTPN | 00 | Program number |
| PTTFT | 01 | File type |
| PTTN | 02 | DD name characters 2 - 8 |
| PTTF | 08 | Flags:
OUT (X’80’) output
BSAM (X’40’) BSAM
BACK (X’20’) read backwards
JCL (X’10’) BLKSIZE/LRECL/RECFM taken from DATADEF statement or label
UNDEF (X’04’) undefined record format
VAR (X’02’) variable record format
|
| - | 09 | Reserved |
| PTTMBS | 0A | Maximum block size |
| - | 0C | Reserved |
The PTT entry for the sequential protection log can be identified by X‘12F1’ in its first two bytes.
The following general rules must be followed when defining Adabas device block sizes:
all block sizes must be multiples of 4
a single block cannot be split between tracks (block size must be less than or equal to the track size)
The following rules apply for Associator and Data Storage blocks:
Associator block size must be greater than one-fourth the size of the largest FDT, and should be large enough to accept definitions in the various administrative blocks (RABN 1 - 30) and in the FCB
The block sizes for Associator and Data Storage should be a multiple of 256, less four bytes (for example, 1020) to save Adabas buffer pool space
The Associator and Data Storage block sizes must be at least 32 less than the sequential block size
Data Storage block size must be greater than: (maximum compressed record length + 10 + padding bytes)
The Work block size must be greater than either (maximum compressed record length + 110) or (Associator block size + 110), whichever is greater.
If ADAM direct addressing is used:
size > (maximum compressed record length + ADAM record length + 24); size > 277 (maximum descriptor length + 24)
However, TEMP and SORT are generally read and written sequentially; therefore, the larger the TEMP/SORT block size, the better.
Block size for TEMP and SORT must be greater than the block size for Data Storage.
The following rules apply for PLOG or SIBA blocks:
The PLOG or SIBA block size must be greater than either (maximum compressed record length + 110) or (Associator block size + 110), whichever is greater.
It is also recommended that PLOG/SIBA be defined larger than the largest Data Storage block size. This avoids increased I/O caused by splitting Data Storage blocks during online ADASAV operations.
The block size (BLKSIZE) of a sequential file is determined as follows:
if PTTF(JCL) then BLKSIZE is taken from file assignment statement or label; if PTTMBS > 0 then BLKSIZE = PTTMBS; if PTTMBS = 0 then if tape then BLKSIZE = 32760; else BLKSIZE = TDCMSBS; else if BLKSIZE in file assignment statement or label then use it; if PTTF(OUT) then if QBLKSIZE > 0 then BLKSIZE = QBLKSIZE; if tape then BLKSIZE = 32760; else BLKSIZE = TDCMSBS; else error.
Note:
QBLKSIZE is an ADARUN
parameter.
The use of hardware compression (IDRC) is not recommended for protection log files. The ADARES BACKOUT function will run much longer when processing compressed data. Also, the BACKOUT function is not supported for compressed data on z/VM systems.
