Previous Topic: 3.2.1.1.2 IBM VTS Report HeadersNext Topic: 3.2.1.3 IBM VTS DASD Cache Analysis (TAPLVB)


3.2.1.2 IBM VTS Performance Overview (TAPLVA)


The CA MICS IBM VTS Performance Overview Report provides a
consolidated view of important VTS metrics.  While each of
the other IBM VTS reports focuses on a particular area of the
VTS (such as the physical tape drives, cache, or virtual
mounts) this overview report provides a consolidated set of
critical performance metrics that quantify the performance,
throughput, and constraining factors such as throttling.
 
Of particular interest are the percentage of VTS DASD cache
virtual volume mount misses, and non-zero throttle
percentages and values.  Cache misses and throttling degrade
the optimal performance of the virtual tape subsystem.
 
The report uses both the distributed and composite VTS
headers, based on the VTS type reported.  These headers and
their content is described in section 3.2.1.1.2.
 
The report body reports on the following measurements from
left to right:
 
Interval count:
 
o Number of Recording Intervals     - INTERVLS
 
Virtual Mounts (virtual mount counts, by type, scratch and
specific, with a further breakdown of specific mounts by hits
and misses. The percentage of cache misses is also provided):
 
o Total Virtual Mounts                    - fffTVM
o Virtual Fast-Ready (Scratch) Mounts     - fffVFRM
o Total Virtual Specific Mounts           - fffVSPM
o Specific Cache-Hit Mounts               - fffVCHM
o Specific Cache-Miss Mounts              - fffVRM
o Percent of specific mounts that were
  cache misses                            - fffPCVMS
 
Data Transferred (data moved in and out of the VTS DASD
cache):
 
o Channel blocks written to cache (1000s) - fffNUMBS
o Estimated Avg channel block blocksize    - fffAVBSZ
o GB Data Read from VTS DASD Cache         - fffDRVV
o GB Data Written to VTS DASD Cache        - fffDWVV
 
  Note:  fffNUMBS is divided by 1000 for reporting.  fffDRVV
  and fffDWVV are divided by 1024 to convert MB to GB for
  reporting.
 
Channel MB/Sec (minimum, average, and maximum MB data per
second passing through z/OS host channels to/from the VTS
DASD cache):
 
o Minimum Channel MB per second  - fffMNPSC
o Average Channel MB per second  - fffPSCH
o Maximum Channel MB per second  - fffMNPSC
 
Compress Ratios (data compression ratios for data written to
cache and data written to physical tape (backstore)):
 
o Compression ratio writes to VTS DASD Cache - fffAVHAR
o Compression ratio writes to Physical Tape  - VDLAVBSR
 
  Note: For a COMPOSITE VTS, the backstore compression ratio
  reported is the maximum found for either the UI or
  SECONDARY VTS in the same time interval.
 
  For the UI and SECONDARY VTSs in a peer-to-peer
  configuration, the compression ratio for writes to the VTS
  DASD cache is not available.
 
Throttle Values (write overrun throttle percent and throttle
value, and overall throttle value):
 
o Write overrun throttle percentage - VDLAVWRO
o Write overrun throttle value      - VDLAVWOT
o Overall total throttle value      - VDLAVTOT
 
  Note: For a COMPOSITE VTS, all three throttle values
  reported are the maximum found from either the UI or
  SECONDARY VTS in the same time interval.
 
At the bottom of the report, a line is generated that shows
summary totals, minimums, maximums, averages, or percentages,
as appropriate for the detailed data in each column.
 
Report data for VTS type COMPOSITE is generated from the
VTS Composite Library Activity (IVTVCL) file.  Report data
for VTS types UI, SECONDARY, and STANDALONE is generated from
the VTS Distributed Library Activity (IVTVDL) file.
 
The throttle values and backstore compression ratio value
reported for the COMPOSITE VTS are determined, during report
code processing, by selecting the maximum value found in
either the UI or SECONDARY VTS for the same time period.

To produce the report:

  o Enter the CA MICS Workstation Facility (MWF)

  o Choose option 2, CA MICS Information Center Facility
    (MICF)

  o Choose option 2, Database Inquiries

  o Select TAPLVA, IBM VTS Performance Overview Report,
    whose Catalog Group is PERFORM

  o Complete the MICF Execution panel

  o Complete the specification panel.  Refer to section
    3.2.1.1.1, IBM VTS MICF Inquiry Specification Panels, for
    information about modifiable panel fields.

IBM VTS Performance Overview (TAPLVA) Report Sample
---------------------------------------------------
The following report sample provides a performance overview
for a day by hour.  The VTS reported is a peer-to-peer
configuration.  The three report pages show the Composite VTS
statistics followed by statistics for the User Interface (UI)
and Secondary VTSs.
 
The report shows a highly active and somewhat constrained
virtual tape system.  The average number of cache misses for
the day is 23%, with a high of 68% at 2:00 PM.
 
In addition, write overrun throttling is occurring during
most hours of the day.  Write overrun throttling results in
degraded z/OS workload performance because the VTS slows down
each write I/O to the DASD cache as it tries to free up
additional cache space.

 Inquiry : TAPLVA                         CA MICS IBM VTS Performance Overview Report  Run Date: 02APRyy                             Data Presented by Hour within Day                                         Page 002    VTS Library ID: K9200             VTC Preferred I/O : NONE           Copy Mode Setting : Mixed      Report Start: 31MARyy:00:00  Library Type  : PtP-COMPOSITE     VTC Preferred Mast: VTS0           VTC Maint Level   : 7414.00    Report End  : 31MARyy:23:00  UI/SEC IDs    : K9229/K9230       F/C 4001 Status   : Enabled                                       Timespan    : DAYS   ----------------------------------------------------------------------------------------------------------------------------------                                                             Day: 31MAYyy               ----------- Virtual Mounts ------------  ---- Data Transferred -----  -Channel MB/Sec-   -Compress--  Throttle Values                                                      1000's    Avg     GB   GB                         Ratios           Avg  Avg       Numb                       Cache  Cache  Pct   Ch Blks  BSize  Cache Cache                                   Wrt  Wrt  Tot  HOUR Intv   Total Scrtch Spcfic  Hits   Miss  Miss  Written  (Est)   Read Write   Min   Avg   Max   Cache BkStr   Pct  Val  Val  ---- ----  ------ ------ ------ ------ ------ ----  -------  -----  ----- -----  ----- ----- -----  ----- -----  ----  ---  ---     0    1     735    323    412    371     41  10%  9597.99  24000  264.8 270.7  152.3 152.3 152.3   2.83  0.96   17%  126   20     1    1     995    430    565    478     87  15%  11768.7  24000  309.7 321.7  179.6 179.6 179.6   4.31  0.96    6%   78    5     2    1    1293    472    821    700    121  15%  14154.8  25000  386.4 402.5  224.4 224.4 224.4   3.93  0.96   14%   97   12     3    1     557    235    322    253     69  21%  12486.4  26000  164.3 295.7  130.9 130.9 130.9   2.86  0.96   16%  119   17     4    1     666    162    504    453     51  10%  5657.33  24000  400.2 135.0  152.2 152.2 152.2   2.29  0.96    7%   70    5     5    1     806    172    634    565     69  11%  8082.00  25000  384.3 208.3  168.6 168.6 168.6   2.59  0.96   15%   88   13     6    1     458    109    349    314     35  10%  7870.23  29000  334.6 233.3  161.5 161.5 161.5   2.39  0.96   10%   48    5     7    1     492    102    390    332     58  15%  6867.42  32000  322.6 222.7  155.1 155.1 155.1   2.73  0.96    7%   80    5     8    1     604    180    424    319    105  25%  8877.53  31000  384.6 286.1  190.8 190.8 190.8   2.66  0.96   15%  100   15     9    1     315    106    209    160     49  23%  6464.37  33000  202.9 204.4  115.8 115.8 115.8   2.67  0.96   11%  113   13    10    1     163     77     86     79      7   8%  5428.42  29000  168.9 166.0   95.3  95.3  95.3   2.63  0.96    1%   16    0    11    1     113     51     62     54      8  13%  5890.89  22000  223.0 141.5  103.7 103.7 103.7   3.64  0.96    0%    4    0    12    1     162     85     77     68      9  12%  8381.00  24000  295.0 243.1  153.1 153.1 153.1   4.45  0.96    0%    0    0    13    1     253     91    162    131     31  19%  5816.76  10000  197.5  65.0   74.7  74.7  74.7   2.54  0.96    0%    0    0    14    1     290     59    231     74    157  68%  1810.21  21000  205.8  43.0   70.8  70.8  70.8   2.16  0.96    0%    0    0    15    1     718    314    404    261    143  35%  6699.79  22000  290.7 164.2  129.4 129.4 129.4   4.08  0.96    0%    0    0    16    1     902    536    366    240    126  34%  14310.8  24000  361.7 349.5  202.3 202.3 202.3   2.97  0.96   23%  110   25    17    1     812    444    368    237    131  36%  23932.3  25000  246.6 493.0  210.4 210.4 210.4   2.65  0.96   68%  122   81    18    1     842    432    410    267    143  35%  24222.4  25000  270.5 473.1  211.5 211.5 211.5   2.77  0.96   44%  125   55    19    1    1061    524    537    397    140  26%  21968.4  24000  470.8 430.6  256.4 256.4 256.4   2.93  0.96   40%  125   44    20    1     947    441    506    359    147  29%  19027.1  25000  402.7 447.6  241.9 241.9 241.9   2.95  0.96   31%  139   43    21    1     951    429    522    373    149  29%  12136.8  25000  596.2 345.1  267.8 267.8 267.8   3.75  0.96   20%   86   18    22    1     689    293    396    279    117  30%  10418.9  24000  399.3 294.7  197.4 197.4 197.4   3.63  0.96   10%   71    7       ----  ------ ------ ------ ------ ------ ----  -------  -----  ----- -----  ----- ----- -----  ----- -----  ----  ---  ---  Tots   23   14824   6067   8757   6764   1993  23%   251871  25000   7283  6237   70.8 184.6 267.8   3.12  0.96   15%   75   17 ----------------------------------------------------------------------------------------------------------------------------------


 Inquiry : TAPLVA                         CA MICS IBM VTS Performance Overview Report  Run Date: 02APRyy                             Data Presented by Hour within Day                                         Page 002    VTS Library ID: K9229             Library Make-Model: 3584-L22       Lib Maint Level:  534.33       Report Start: 31MARyy:00:00  Library Type  : PtP-UI            VTS Cache Size    : 1728 GB        VTS Maint Level: 7414.00       Report End  : 31MARyy:23:00  Composite ID  : K9200             F/C 4001 Status   : Enabled                                       Timespan    : DAYS   ----------------------------------------------------------------------------------------------------------------------------------                                                             Day: 31MAYyy               ----------- Virtual Mounts ------------  ---- Data Transferred -----  -Channel MB/Sec-   -Compress--  Throttle Values                                                      1000's    Avg     GB   GB                         Ratios           Avg  Avg       Numb                       Cache  Cache  Pct   Ch Blks  BSize  Cache Cache                                   Wrt  Wrt  Tot  HOUR Intv   Total Scrtch Spcfic  Hits   Miss  Miss  Written  (Est)   Read Write   Min   Avg   Max   Cache BkStr   Pct  Val  Val  ---- ----  ------ ------ ------ ------ ------ ----  -------  -----  ----- -----  ----- ----- -----  ----- -----  ----  ---  ---     0    1     737    489    248    223     25  10%  6197.62  10000   36.0  54.9   25.9  25.9  25.9    n/a  0.95   17%  118   20     1    1     997    697    300    247     53  18%  4555.16   8000   40.8  27.7   19.5  19.5  19.5    n/a  0.95    4%   56    2     2    1    1300    885    415    349     66  16%  6534.91   9000   37.6  44.6   23.4  23.4  23.4    n/a  0.95   14%   90   12     3    1     564    411    153    111     42  27%  3909.93  12000   28.0  40.2   19.4  19.4  19.4    n/a  0.95   13%  119   15     4    1     669    432    237    209     28  12%  2630.00  13000   56.2  29.0   24.2  24.2  24.2    n/a  0.95    7%   70    5     5    1     815    484    331    279     52  16%  3471.86  14000   82.1  40.0   34.7  34.7  34.7    n/a  0.95   10%   88    9     6    1     465    281    184    156     28  15%  2884.17  13000   77.1  32.2   31.1  31.1  31.1    n/a  0.95   10%   48    5     7    1     495    283    212    164     48  23%  3180.23  11000   64.9  30.8   27.2  27.2  27.2    n/a  0.95    6%   80    5     8    1     606    385    221    165     56  25%  4921.94  15000   72.0  66.9   39.5  39.5  39.5    n/a  0.95   15%  100   15     9    1     316    202    114     89     25  22%  3726.05  15000   36.7  47.8   24.0  24.0  24.0    n/a  0.95    5%   66    3    10    1     162    109     53     49      4   8%  3356.84  10000   31.3  31.5   17.9  17.9  17.9    n/a  0.95    1%    7    0    11    1     114     79     35     28      7  20%  2936.40  10000   45.9  22.3   19.4  19.4  19.4    n/a  0.95    0%    4    0    12    1     162    116     46     40      6  13%  1839.08  12000   32.6  17.7   14.3  14.3  14.3    n/a  0.95    0%    0    0    13    1     256    156    100     84     16  16%  3416.38   7000   46.5  17.5   18.2  18.2  18.2    n/a  0.95    0%    0    0    14    1     290    157    133     31    102  77%   935.95   7000   40.8   6.1   13.4  13.4  13.4    n/a  0.95    0%    0    0    15    1     720    510    210    127     83  40%  3483.47   6000   48.3  17.6   18.8  18.8  18.8    n/a  0.95    0%    0    0    16    1     907    721    186    124     62  33%  11387.0   9000   64.0  82.2   41.6  41.6  41.6    n/a  0.95   23%  110   25    17    1     817    617    200    134     66  33%  9818.39  10000   43.3  82.6   35.8  35.8  35.8    n/a  0.95   56%  122   69    18    1     853    626    227    150     77  34%  12722.5   8000   43.0  85.0   36.4  36.4  36.4    n/a  0.95   41%  118   49    19    1    1064    795    269    191     78  29%  12077.6   9000   40.8  85.6   36.0  36.0  36.0    n/a  0.95   35%  125   44    20    1     957    687    270    165    105  39%  8426.56  10000   49.3  70.7   34.1  34.1  34.1    n/a  0.95   31%  135   43    21    1     958    688    270    185     85  31%  5507.64   8000   64.4  36.6   28.7  28.7  28.7    n/a  0.95   14%   82   11    22    1     701    500    201    128     73  36%  5048.19  10000   51.3  36.0   24.8  24.8  24.8    n/a  0.95    3%   28    0       ----  ------ ------ ------ ------ ------ ----  -------  -----  ----- -----  ----- ----- -----  ----- -----  ----  ---  ---  Tots   23   14925  10310   4615   3428   1187  26%   122968  10000   1133  1006   13.4  28.9  41.6    n/a  0.95   13%   68   14 ----------------------------------------------------------------------------------------------------------------------------------


 Inquiry : TAPLVA                         CA MICS IBM VTS Performance Overview Report  Run Date: 02APRyy                             Data Presented by Hour within Day                                         Page 002    VTS Library ID: K9230             Library Make-Model: 3584-L22       Lib Maint Level:  534.33       Report Start: 31MARyy:00:00  Library Type  : PtP-SECONDARY     VTS Cache Size    : 1728 GB        VTS Maint Level: 7414.00       Report End  : 31MARyy:23:00  Composite ID  : K9200             F/C 4001 Status   : Enabled                                       Timespan    : DAYS   ----------------------------------------------------------------------------------------------------------------------------------                                                             Day: 31MAYyy               ----------- Virtual Mounts ------------  ---- Data Transferred -----  -Channel MB/Sec-   -Compress--  Throttle Values                                                      1000's    Avg     GB   GB                         Ratios           Avg  Avg       Numb                       Cache  Cache  Pct   Ch Blks  BSize  Cache Cache                                   Wrt  Wrt  Tot  HOUR Intv   Total Scrtch Spcfic  Hits   Miss  Miss  Written  (Est)   Read Write   Min   Avg   Max   Cache BkStr   Pct  Val  Val  ---- ----  ------ ------ ------ ------ ------ ----  -------  -----  ----- -----  ----- ----- -----  ----- -----  ----  ---  ---     0    1     783    596    187    149     38  20%  5344.43  12000   32.4  52.9   24.3  24.3  24.3    n/a  0.96   14%  126   17     1    1     878    665    213    171     42  20%  5336.95   9000   32.6  37.2   19.9  19.9  19.9    n/a  0.96    6%   78    5     2    1    1241    857    384    323     61  16%  10451.3   8000   43.9  67.4   31.6  31.6  31.6    n/a  0.96   10%   97   10     3    1     793    539    254    202     52  20%  6298.51  11000   22.4  56.5   22.4  22.4  22.4    n/a  0.96   16%  107   17     4    1     632    383    249    211     38  15%  4025.96  11000   64.4  37.6   29.0  29.0  29.0    n/a  0.96    3%   27    0     5    1     813    497    316    260     56  18%  3624.19  12000   65.4  36.6   29.0  29.0  29.0    n/a  0.96   15%   87   13     6    1     502    322    180    154     26  14%  4391.89  15000   69.4  54.2   35.2  35.2  35.2    n/a  0.96   10%   47    4     7    1     473    299    174    151     23  13%  4943.93  14000   61.4  62.4   35.2  35.2  35.2    n/a  0.96    7%   70    5     8    1     618    402    216    163     53  25%  3953.12  11000   73.0  38.3   31.7  31.7  31.7    n/a  0.96    9%   60    5     9    1     389    265    124     87     37  30%  2665.91  15000   40.4  33.6   21.1  21.1  21.1    n/a  0.96   11%  113   13    10    1     177    138     39     27     12  31%  2776.55  12000   22.2  27.5   14.1  14.1  14.1    n/a  0.96    1%   16    0    11    1     109     85     24     23      1   4%  3120.59   8000   36.6  22.1   16.7  16.7  16.7    n/a  0.96    0%    4    0    12    1     180    142     38     32      6  16%  4494.83   8000   42.3  25.9   19.4  19.4  19.4    n/a  0.96    0%    0    0    13    1     204    159     45     39      6  13%  3481.19   5000   27.9  12.3   11.4  11.4  11.4    n/a  0.96    0%    0    0    14    1     307    205    102     33     69  68%  1185.96  18000   47.8  17.5   18.6  18.6  18.6    n/a  0.96    0%    0    0    15    1     514    378    136     65     71  52%  2008.53   9000   36.5  15.2   14.7  14.7  14.7    n/a  0.96    0%    0    0    16    1     894    684    210    145     65  31%  8738.10   9000   61.5  58.4   34.1  34.1  34.1    n/a  0.96    5%   54    3    17    1     947    755    192    124     68  35%  10299.0  11000   54.2  91.7   41.5  41.5  41.5    n/a  0.96   68%  119   81    18    1     776    600    176    101     75  43%  9893.41   9000   55.4  71.5   36.1  36.1  36.1    n/a  0.96   44%  125   55    19    1     823    650    173    103     70  40%  10817.9   8000   56.8  71.4   36.5  36.5  36.5    n/a  0.96   40%  110   44    20    1    1121    796    325    226     99  30%  9530.00   9000   65.3  68.9   38.2  38.2  38.2    n/a  0.96   23%  139   32    21    1     962    720    242    163     79  33%  7405.04  10000   72.7  63.3   38.7  38.7  38.7    n/a  0.96   20%   86   18    22    1     852    603    249    161     88  35%  4585.70  11000   63.0  41.0   29.6  29.6  29.6    n/a  0.96   10%   71    7       ----  ------ ------ ------ ------ ------ ----  -------  -----  ----- -----  ----- ----- -----  ----- -----  ----  ---  ---  Tots   23   14988  10740   4248   3113   1135  27%   129373  10000   1147  1063   11.4  30.2  41.5    n/a  0.96   14%   67   14 ----------------------------------------------------------------------------------------------------------------------------------


Figure 3-5.  IBM VTS Performance Overview