Service machines can be
improved by following the suggestions described below.
Increase virtual storage for the DIRMAINT machine to 32 or 48Meg.
Split the CONFIG DATADVH file into multiple files.
Minimize the number of entries in the following lists:
REQUIRED_SERVER_FILE
REQUIRED_DIRMAINT_FILE
REQUIRED_DATAMOVE_FILE
REQUIRED_DIRMSAT_FILE
List all of the following
common parts on LOADABLE_SERV_FILE entries:
DVHWAIT
DVHWAKE
DVHWAKE3
DVHRDR
DVHDF8
DVHRQST
DVHFNDCS
DVHCEXIT
DVHMSG
DVHXLF
DVHESMLR
DVHRACLR
DVHSHUT
List DVHDMCTL on
LOADABLE_DATAMOVE_FILE entries.
List DVHDSCTL on
LOADABLE_DIRMSAT_FILE entries.
List all executable DirMaint parts; file names beginning DVH and
file types of EXEC, MODULE, REXX, or XEDIT not already on
a LOADABLE_xxxxxxxx_FILE entry or a
LOADABLE_DIRMAINT_FILE entry.
Consider installing all of the
LOADABLE_xxxxxxxx_FILE entries into a shared segment.
Use existing system facilities for disaster recovery, rather than
exploit DirMaint's redundancy capabilities.
Don't use the 2AA disk if the 1AA disk is backed up nightly.
Don't use the 2DF disk if the 1DF disk is backed up nightly.
Don't use the MESSAGE_LOGGING_FILETYPE if you are
running with an ESM and recording DirMaint activity in the ESM audit log.
Use the MESSAGE_LOGGING_FILTER_EXIT
and ESM_LOG_FILTER_EXIT
entries to avoid recording unnecessary messages in the TRANSLOG file or
in the ESM audit log.
Exploit tailoring options that improve both performance and usability
on your system.
For example, use UPDATE_IN_PLACE= YES on your system.
Avoid using options whose performance cost on your system outweighs
the usability benefits for your system.
Avoid use of SORT_BY_DEVICE_ADDRESS= YES.
Use DASD_ALLOCATE= FIRST_FIT rather than EXACT_FF.
If privacy of residual data is not usually a concern on your system,
use DISK_CLEANUP= NO to avoid the time to FORMAT deleted minidisks.
Experiment with options that have trade-offs that could fall
either way.
Try ONLINE= IMMED; the WRK_UNIT_ONLINE setting is irrelevant.
Try ONLINE= SCHED with WRK_UNIT_ONLINE= YES.
Try ONLINE= SCHED with WRK_UNIT_ONLINE= NO.
With ONLINE= IMMED or with WRK_UNIT_ONLINE= YES,
try the IBM supplied default queue sizes:
specified in the DIRMAINT DATADVH file,
and approximately 30 DASD management commands (AMDISK, CMDISK, DMDISK)
arriving per hour, try increasing the queue sizes:
Customize the DVHXPROF EXEC, an IBM-supplied sample exit routine
to define VFB-512 virtual disks in storage and initialize them
using the following steps:
Customize the DVHPROFA DIRMAINT, DVHPROFA DIRMSAT
and DVHPROFM DATADVH files with the changes
as shown for (1) to (6) in the following table:
(1) PURPOSE= RWS FM= A ACC= 255 V-disk copy of 155.
(2) PURPOSE= SRV FM= C ACC= 291 V-disk copy of 191.
(3) PURPOSE= USR FM= D ACC= 31F V-disk copy of 11F.
(4) PURPOSE= PDF FM= E ACC= 3DF V-disk copy of 1DF.
PURPOSE= PDB FM= G ACC= 1DB
PURPOSE= PTH FM= H ACC= 1AA
(3) PURPOSE= SDF FM= J ACC= 1DF
/ PURPOSE= SDB FM= - ACC= --- not used. PDB covered by nightly backup
/ PURPOSE= STH FM= - ACC= --- not used. PTH covered by nightly backup
(4) PURPOSE= abc FM= K ACC= 155
(5) PURPOSE= def FM= L ACC= 191
(6) PURPOSE= ghi FM= M ACC= 11F
PURPOSE= SFA FM= Z ACC= 2FA V-disk.
Create the V-disks for the 255, 291, 2FA, 31F, and 3DF disks
prior to starting the DirMaint servers. For example modify the
sample profile exec adding define and format commands.
Copy files to the 255, 291, 31F, and 3DF
V-disks from the 155, 191, 11F, and 1DF disks within
the DVHXPROF EXEC, with nothing being copied to the 2FA disk.
Remove comments lines, beginning with a slash,
from the CONFIG* DATADVH file(s).
Exploit the exit routines for performance.
If you have a central administration staff and do not delegate use of
the privileged commands, for example:
/* */ Exit 0
or
/* */
If WordPos(Userid(),'adminid1 adminid2 adminid3') <> 0
Then Exit 0
Else Exit 30
for some of the exit routines will bypass further authorization checking.
Candidates for this include:
SET QDROP OFF Option (370 Feature Only)
This option eliminates the overhead in CP caused by scanning
DirMaint page and segment tables.
SET FAVORED Option (370 Feature Only)
This option prevents DirMaint from being
dropped from the CP scheduler queue although in a wait state.
SET RESERVE Command (Both 370 and ESA Features)
On systems with high paging load, DirMaint
will very likely be paged out when an interrupt comes in.
The SET RESERVE command, however, lets
most DirMaint active pages remain in real storage.
Dispatching Priority (370 Feature Only)
A priority can be specified on the USER control statement for
DirMaint in the VM directory.
SET QUICKDSP Command (ESA Feature Only)
The QUICKDSP designation is intended for selective use on virtual
machines with critical response time requirements. The scheduler
always moves a QUICKDSP user immediately into the dispatch list whenever
it is ready to run, regardless of resource requirements and current
system load. Indiscriminate use, therefore, increases response
time overall and may severely affect maintenance of system storage.
APAR VM60054 / PTF UV59418
Improves performance in handling of the AMDISK
processing for an ADD user and the DMDISK processing for a PURGEd user
in-line. The following must be considered when using the enhancements
provided by this APAR:
DirMaint does not do overlap checking when adding minidisks
Many of the DirMaint exit points cannot be utilized.
Disk cleanup is not performed
APAR VM60684 / PTF UV59845
Improved efficiency when writing updated files to disk by
writing them to the E-disk with a new name, then use
erase and rename. Improvements were also made in the use of pipelines
to change a single record in the USER DIRECT file without having to
rewrite the entire file. And the message repositories and several data
files are now EXECLOADable.
If you'd like to contact DirMaint development and support, you can
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