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Source: VCADAA file at the DETAIL timespan
VCAVOA file at the DETAIL timespan
Function: Identifies problems with your DASD volumes that
could lead to a loss of performance or
availability.
Improves reliability by revealing unidentified
problems before any loss of performance or
availability is experienced.
Helps identify potential space shortage or
fragmentation problems before they become serious.
Identifies the seek distances between the VTOC and
the VVDS and between the VTOC and the index.
These are used to identify seek delays that may
occur if the distances are too great.
Features: The error flags on the right side of the report
identify potential problems quickly, while the
information on the left side will give more
detailed information. A correction jobstream can
also be generated to correct some problems.
SMS
Issues: Users planning for SMS or similar products can
correct problems that would delay their
implementation, such as potential VVDS size
problems.
This report calculates actual and estimated VVDS
sizes, based on the number of data sets in the
volume. The size estimate is based on the larger
record sizes needed if SMS controls the volume.
COLUMN DESCRIPTIONS
Volume Serial Number
The volume serial number of the storage medium.
% Free Space in VTOC
The percentage of unused Data Set Control Blocks
(DSCBs) in the Volume Table of Contents (VTOC) for
this volume. Each unused DSCB represents one new
data set that can be allocated on this volume,
assuming free space on the volume itself is
available. If this number falls below 10%, there
is a possibility that the VTOC will become full,
and no new allocations can be made on the volume.
% Free Space on Volume
The percentage of total tracks on the volume that
remain available for the allocation of new data
sets. If this number falls below 10%, there is a
possibility that the volume will become full, and
no new allocations can be made on it.
Frag. Index
A measure of how fragmented the allocated space is
on this volume.
VTOC Size Trks
The total number of tracks allocated to the VTOC
portion of each volume. The VTOC serves as a
table of contents for the volume, and will contain
at least one entry for each data set allocated on
the volume. The size and location of the VTOC is
established when a new volume is initialized
before its first use. Failure to specify a large
enough value may cause the VTOC to run out of
space, so that no new data sets can be allocated
on the volume, even if unallocated space is still
available.
Index #of Ext
The VTOC Index is an optional structure that may
be allocated on the volume to increase the speed
with which a data set can be located on the
volume. It helps improve volume performance,
especially for volumes with a large number of data
sets, such as TSO volumes. If this column is
zero, no VTOC Index data set exists. If this
column contains a value greater than one, the
Index has expanded into multiple extents across
the volume, and poor performance or Index space
shortages could result. Note that a VTOC Index is
required for volumes that will be managed by SMS.
Index Trks Aloc
The VTOC Index is an optional structure that can
be allocated on the volume to increase the speed
with which a data set can be located on the
volume. It helps improve volume performance,
especially for volumes with a large number of data
sets, such as TSO volumes. This column represents
the total number of tracks that are currently
being used to contain the index for this volume.
If this column is zero, no VTOC Index data set
exists. Note that a VTOC Index is required for
volumes that will be managed by SMS.
VVDS #of Ext
This column represents the number of track extents
(Sections) on this volume used to contain the VSAM
Volume Data Set (VVDS). Prior to SMS, a VVDS was
required if the volume contained VSAM data sets,
as it was used to store additional VSAM
information not kept in the catalog. All volumes
that will be managed by SMS require a VVDS, even
if the volume will contain no VSAM data sets. If
this column is zero, no VVDS data set exists. If
this column contains a value greater than one, the
VVDS has expanded into multiple extents across the
volume, and poor performance or VVDS space
shortages could result.
VVDS Trks Aloc
This column represents the number of tracks on
this volume used to contain the VSAM Volume Data
Set (VVDS). Prior to SMS, a VVDS was required if
the volume contained VSAM data sets, as it was
used to store additional VSAM information not kept
in the catalog. All volumes that will be managed
by SMS require a VVDS, even if the volume will
contain no VSAM data sets. If this column is
zero, no VVDS data set exists. If this column
contains a small value, it is possible the VVDS
could run out of space when new data sets are
created on it, or when the volume is converted to
SMS management.
VVDS Trks Reqd
This column represents an estimate of the number
of tracks that should exist in the VVDS to
represent the data sets currently contained on the
volume. The calculation used to derive this value
uses the larger values that are required if the
volume is to be managed by SMS. If no VVDS exists
on the volume, you can use this as an
approximation if you decide to add one. If the
volume already has a VVDS and you are considering
SMS management of it, compare this column with the
VVDS Trks Aloc column to see if a size problem
might exist after conversion to SMS.
Seek VVDS Cyls
The approximate distance, in cylinders, between
the start of the VTOC on this volume and the start
of the VVDS. Placement of the VTOC and the VVDS
in the same general location on the volume can
improve performance, as it reduces the distance
the read head must travel between the two
structures. Large values in this column could
indicate potential performance problems, caused by
excessive seeking. This value will be zero if no
VVDS exists on the volume.
Seek Index Cyls
The approximate distance, in cylinders, between
the start of the VTOC on this volume and the start
of the VTOC Index. Placement of the VTOC and the
Index in the same general location on the volume
can improve performance, as it reduces the
distance the read head must travel between the two
structures. Large values in this column could
indicate potential performance problems, caused by
excessive seeking. This value will be zero if no
VTOC Index exists on the volume.
DIRF Set
This data set is updated when a non-MVS operating
system has added or deleted a data set on the
volume without updating the free space
information.
No INDX
An asterisk (*) will appear under this column if
no VTOC Index data set exists for this volume.
INDX Off
An asterisk (*) will appear under this column if a
VTOC Index is not active for this volume. This
can be caused by one of three conditions:
1) No index data set has been allocated on the
volume. The No INDX column should contain an
asterisk also.
2) An index data set has been defined, but it has
never been activated using the IBM DSF utility
program.
3) An index data set was defined and activated,
but a hardware or software error has
deactivated it. The IBM DSF utility program
should be used to reactivate it.
Alt Trks
An asterisk (*) will appear under this column if
one or more of the alternate tracks on the volume
have been assigned. Alternate tracks are assigned
when a hardware error has occurred, and the
defective track is replaced by one of the
alternates. Element VOANOATK in the VCAVOA file
can be examined to determine the actual number of
alternate tracks that have been assigned.
Mis Trks
An asterisk (*) will appear under this column if
the VCC collector detected missing tracks when the
data for this volume was collected. This can be
caused by the volume not being serialized when the
data was collected (refer to your VCC run
options), or by actual structure errors in the
VTOC. Element VOASPACM in the VCAVOA file can be
examined to determine the actual number of missing
tracks that were detected.
VVDS Size
An asterisk (*) will appear under this column if
no VVDS was found on the volume, or if the current
VVDS size (VDS Trks Aloc) is smaller than the
estimated VVDS size required (VVDS Trks Reqd).
Seek Dist
An asterisk (*) will appear under this column if
the sum of the two seek values (Seek VVDS Cyls and
Seek Index Cyls) exceeds 50 cylinders. This might
indicate potential performance problems due to the
locations of the VTOC, VTOC Index and VVDS
structures.
VOLUME PROBLEMS (STGECA) 1 CA MICS StorageMate ABC CORPORATION ----------------------------------------- System Identifier=TST1 Device Type=3380-K --------------------------------------------- Volume % Free % Free Frag. VTOC +-Index-+ +---- VVDS ----+ +--Seek--+ +---------- Error Indicators ----------+ Serial Space Space on Index Size #of Trks #of Trks Trks VVDS Index DIRF No INDX Alt Mis VVDS Seek Number in VTOC Volume Trks Ext Aloc Ext Aloc Reqd Cyls Cyls Set INDX Off Trks Trks Size Dist DMSC56 100 99 0.000 59 00 0 00 0 1 0 0 * * * DMS995 100 99 0.001 29 01 175 01 10 1 10 13 EITO1A 83 14 0.019 12 01 2 01 10 1 5 1 EITO2A 94 83 0.051 12 01 2 01 10 1 16 1 EITS01 74 35 0.039 15 00 0 01 30 1 543 0 * * * EITS02 54 5 0.289 14 00 0 01 3 2 362 0 * * * EITS03 67 30 0.039 15 00 0 01 30 1 688 0 * * * EITS04 72 37 0.046 15 00 0 01 10 1 1766 0 * * * EITS05 77 59 0.101 15 00 0 01 10 1 325 0 * * * NCPD81 96 88 0.064 29 00 0 01 10 1 201 0 * * * SMSCAT 98 46 0.000 14 01 14 01 3 1 8 1 * SMSE02 96 42 0.250 44 01 14 01 10 1 14 3 * SMSPG1 96 30 0.050 14 01 14 01 3 1 3 1 * V10001 87 35 0.258 44 01 9 01 30 2 4 3 V10003 90 43 0.280 44 01 9 01 30 2 4 3 * V10004 88 21 0.328 44 01 9 01 30 2 4 3 HSM902 51 38 0.402 59 01 15 00 0 5 0 4 * SMSJS1 94 0 0.000 1 00 0 00 0 1 0 0 * * *
Figure 4-78. Volume Problems
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