Detail VMX DASD Cache Usage Report (by Device)
Detail VMX DASD Cache Usage Report (by Device) produces a tabular listing of cache usage on 3880-23 and 3990-3 control units by VOLSER for the duration of the period specified in the run-time execution parameters.
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The report is in two formats: one for 3880-23 controllers and one for 3990-3 controllers. These are identified by the report titles.
Intended use
For analysis of cache usage in terms of how much activity is directed to cache VOLSERs; whether transfers to and from DASD are being avoided by using cache; and what percentage of bytes read are from cache, from DASD bypassing cache, and from DASD due to read misses. This report can be used to detect when cache is being utilized inefficiently, and for monitoring changes to the cache environment.
Format 3880-23 Control Units:
A tabular report, in ascending order, of device address where each column represents a different measurement associated with a given VOLSER:
READ HIT RATIO
The ratio of the sum of all "search and read normal" and "search and read sequential" requests that were satisfied from cache to the total number of read requests to the volume.
WRITE/READ RATIO
The ratio of the sum of all "write normal" and "write sequential" requests to the sum of all "search and read normal" and "search and read sequential" requests.
READ REQUESTS
The sum of all "search and read normal" and "search and read sequential" requests to the volume.
WRITE REQUESTS
the sum of all "write normal" and "write sequential" requests.
PCT OF DASD READ CACHE
The percentage of all bytes transferred from this VOLSER that were transferred from cache to the channel without DASD access.
PCT OF DASD READ DASD
The percentage of all bytes transferred from this VOLSER that were transferred from DASD to cache to the channel due to read misses.
PCT OF DASD READ BYPASS
The percentage of all bytes transferred from this VOLSER that were transferred from DASD to the channel, bypassing cache access.
An example of this report is shown in the figures Detail VMX 3880-23 Cache Usage Report (by Device) and Detail VMX 3990-3 Cache Usage Report (by Device).
Inquiry ID
- Tabular Report: VMXTXB
Data Source (File/Timespan):
VMXCDI01 - DETAIL
Data elements used
- VMXDVSID
- Host Subchannel ID
- CDISDID
- Storage Director Identification
- CDICUTYP
- Control Unit Type
- CDIOCSTA
- Overall Caching Status
- CDICAPAV
- Available Subsystem Storage Capacity
- CDICAPOF
- Offline Subsystem Storage Capacity
- CDISRNRQ
- Search and Read Normal Requests
- CDISRSRQ
- Search and Read Sequential Requests
- CDISRNRH
- Search and Read Normal Request Hits
- CDISRSRH
- Search and Read Sequential Request Hits
- CDIWNRQ
- Write Normal Requests
- CDIWSQRQ
- Write Sequential Requests
- CDIDACBX
- Bytes Transferred From DASD To Channel
- CDICACBX
- Bytes Transferred From Cache To Channel
- CDIDCCBX
- Bytes Xfr From DASD To Cache and Channel
Calculations
A number of elements are calculated to produce this report. They are as follows:
READREQ = CDISRNRQ + CDISRSRQ; WRITEREQ = CDIWNRQ + CDIWSQRQ; IF READREQ > 0 THEN DO; RHRATIO = 100 * ((CDISRNRH + CDISRSRH) / READREQ); WRRATIO = 100 * (WRITEREQ / READREQ); END; ELSE DO; RHRATIO = 0; WRRATIO = 0; END; BYTEXFRD = SUM(CDIDACBX,CDICACBX,CDIDCCBX); IF BYTEXFRD > 0 THEN DO; CACHE = 100 * (CDICACBX / BYTEXFRD); DASD = 100 * (CDIDCCBX / BYTEXFRD); BYPASS = 100 * (CDIDACBX / BYTESFRD); END; ELSE DO; CACHE = 0; DASD = 0; BYPASS = 0; END;
Usage considerations
None
Detail VMX 3880-23 Cache Usage Report (by Device) Sample
------------------------------------------------------------------------------------------------------------------------------------ VM Cache Usage Detail ReportBroadcomProduction Complex INQUIRY: VMXTXB RUN DATE: 14DECyy System: VMXA Date: 13DECyy CU Type: 3880-23 Stg Dir Id: 0E Device Id: 77 Device: 0977 Volume: MVSC1A ------------------------------------------------------------------------------------------------------------------------------------ Read Write Percent Of Read I/Os Overall Hit Read Read Write -------------------- Capacity Cache Stat Time Ratio Ratio Requests Requests Cache DASD Bypass Available <------------------> ------------------------------------------------------------------------------------------------------------------------------------ 8:45 86.27 0.00 51 0 77.83 22.17 0.00 414.87 ACT --- --- CU0 CU1 9:00 84.08 1.20 333 4 76.17 23.83 0.00 287.22 ACT --- --- CU0 CU1 9:15 94.06 59.58 522 311 93.84 6.12 0.05 319.13 ACT --- --- CU0 CU1 9:30 97.44 90.74 821 745 97.85 2.14 0.01 414.87 ACT --- --- CU0 CU1 9:45 99.29 98.40 564 555 99.80 0.14 0.06 351.05 ACT --- --- CU0 CU1 10:00 100.00 100.00 488 488 100.00 0.00 0.00 287.22 ACT --- --- CU0 CU1 10:15 99.06 92.94 425 395 99.77 0.20 0.02 382.96 ACT --- --- CU0 CU1 10:30 99.08 93.58 436 408 99.84 0.16 0.00 351.05 ACT --- --- CU0 CU1 10:45 100.00 95.69 418 400 100.00 0.00 0.00 351.05 ACT --- --- CU0 CU1 11:00 99.04 97.50 519 506 99.70 0.30 0.00 319.13 ACT --- --- CU0 CU1 11:15 99.78 99.56 457 455 99.99 0.01 0.00 287.22 ACT --- --- CU0 CU1 11:30 97.42 90.96 542 493 96.78 3.09 0.13 351.05 ACT --- --- CU0 CU1 11:45 100.00 106.36 393 418 100.00 0.00 0.00 319.13 ACT --- --- CU0 CU1 12:00 99.69 99.69 636 634 99.89 0.11 0.00 382.96 ACT --- --- CU0 CU1 ------------------------------------------------------------------------------------------------------------------------------------
Detail VMX 3990-3 Cache Usage Report (by Device) Sample
------------------------------------------------------------------------------------------------------------------------------------ Detail VM Cache Usage ReportBroadcomProduction Complex INQUIRY: VMXTXB RUN DATE: 14DECyy System: VMXA Date: 13DECyy CU Type: 3990-3 Subsystem Id: 10 Device Id: E0 Device: 08E0 Volume: XAP002 ----------------------------------------------------------------------------------------------------------------------------------- Basic DASD F/W Cache F/W < Capacity > < Status > R-Hit R-Wrt W-Hit Oflow R-Hit W-Hit < Cache > NVS < Cache > < NVS > < Device > Time <-- Ratio --> <Ratio Rate> <-- Ratio --> Available In Error In Error Act Err Act Err Act DFW Duplex Err Pin ----------------------------------------------------------------------------------------------------------------------------------- 8:45 76.32 0.05 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 9:00 23.19 0.09 0.00 0.00 0.00 0.00 444.28 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 9:15 27.17 0.22 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 9:30 68.39 0.48 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 9:45 80.62 0.39 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 10:00 35.21 0.09 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 10:15 45.95 0.12 0.00 0.00 0.00 0.00 444.28 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 10:30 30.43 0.02 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 10:45 19.44 0.05 0.00 0.00 0.00 0.00 444.28 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 11:00 20.00 0.01 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 11:15 35.00 0.03 0.00 0.00 0.00 0.00 380.81 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 11:30 37.07 0.19 0.00 0.00 0.00 0.00 476.02 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 11:45 56.44 0.37 0.00 0.00 0.00 0.00 444.28 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO 12:00 56.73 0.16 0.00 0.00 0.00 0.00 380.81 0.00 0.00 ACTV CFD DACT --- ACT DAC NO -- --- NO ------------------------------------------------------------------------------------------------------------------------------------