A speedtest is a diagnostic test that writes random data from the publisher to a specific engine (Apply Engine or Replicator) to measure the network throughput. It is "best case" throughput. Normal publishing is suspended for the test, and the engine reads and discards test data without acknowledgement. Running a speedtest will, therefore, affect publisher latency.
Test start and end summary messages are written as WTO and to SYSPRINT in the publisher and are mirrored in the console log (stderr) on the engine side. Histograms like those written for netstats are written to the publisher's SYSPRINT.
A speedtest is independent of netstats and can be run with or without netstats being enabled. Speedtest I/O counts are not included in netstats measurements.
A speedtest is initiated from the publisher to a specific target by SQDCONF tune command. The amount of data is determined by --count and --size arguments. Generally, using a size that is approximately that of the average CDC record size for the engine and a count that yields a total payload ranging from 1 to 10 gigabytes of data will provide a reasonable measure. For the target, specify only the engine subscription name, not the full URL.
//SPEED EXEC PGM=SQDCONF,REGION=32M
//STEPLIB DD DISP=SHR,DSN=<sqdata load library>
//SYSPRINT DD SYSOUT=*
//SYSOUT DD SYSOUT=*
//SQDLOG DD SYSOUT=*
//SQDPARMS DD *
tune --speedtest --target=ENGINE2 --size=1000 --count=1700000
<cab file>
/*12.56.18 S0079331 SQDT005I Start speedtest 1700000 1000-byte records (1.58325 GiB) for 014
014 cdc:////ENGINE2
12.56.36 S0079331 SQDT005I End speedtest elapsed 00:00:17.672941 (91.7361 MiB/s) 129
129 writes:1703304 retries:3303 timeouts:0 for cdc:////ENGINE2SQDT005I Start speedtest 1700000 1000-byte records (1.58325 GiB) for cdc:////ENGINE2
SQDS002I Stats: cdc:////ENGINE2 write message in microseconds
SQDS001I events: 1700000 avg:7.7
SQDS003I < 2 : 465961 ( 27.41%) *****
SQDS003I < 3 : 534604 ( 31.45%) ******
SQDS003I < 4 : 23597 ( 1.39%)
SQDS003I < 5 : 173201 ( 10.19%) **
SQDS003I < 6 : 266883 ( 15.70%) ***
SQDS003I < 7 : 88049 ( 5.18%) *
SQDS003I < 8 : 23628 ( 1.39%)
SQDS003I < 9 : 11675 ( 0.69%)
SQDS003I < 10 : 7948 ( 0.47%)
SQDS003I < 20 : 33899 ( 1.99%)
SQDS003I < 30 : 20952 ( 1.23%)
SQDS003I < 40 : 13130 ( 0.77%)
SQDS003I < 50 : 8269 ( 0.49%)
SQDS003I < 60 : 5538 ( 0.33%)
SQDS003I < 70 : 3774 ( 0.22%)
SQDS003I < 80 : 2771 ( 0.16%)
SQDS003I < 90 : 2174 ( 0.13%)
SQDS003I < 100 : 1687 ( 0.10%)
SQDS003I < 200 : 6645 ( 0.39%)
SQDS003I < 300 : 1931 ( 0.11%)
SQDS003I < 400 : 1175 ( 0.07%)
SQDS003I < 500 : 746 ( 0.04%)
SQDS003I < 600 : 386 ( 0.02%)
SQDS003I < 700 : 260 ( 0.02%)
SQDS003I < 800 : 211 ( 0.01%)
SQDS003I < 900 : 152 ( 0.01%)
SQDS003I < 1K : 101 ( 0.01%)
SQDS003I < 2K : 415 ( 0.02%)
SQDS003I < 3K : 91 ( 0.01%)
SQDS003I < 4K : 36 ( 0.00%)
SQDS003I < 5K : 24 ( 0.00%)
SQDS003I < 6K : 13 ( 0.00%)
SQDS003I < 7K : 10 ( 0.00%)
SQDS003I < 8K : 8 ( 0.00%)
SQDS003I < 9K : 5 ( 0.00%)
SQDS003I < 10K : 7 ( 0.00%)
SQDS003I < 20K : 23 ( 0.00%)
SQDS003I < 30K : 7 ( 0.00%)
SQDS003I < 40K : 3 ( 0.00%)
SQDS003I < 50K : 2 ( 0.00%)
SQDS003I < 60K : 2 ( 0.00%)
SQDS003I < 70K : 2 ( 0.00%)
SQDS003I < 80K : 1 ( 0.00%)
SQDS003I < 90K : 0 ( 0.00%)
SQDS003I < 100K : 2 ( 0.00%)
SQDS003I < 200K : 2 ( 0.00%)
SQDS000I -----------------
SQDS002I Stats: cdc:////ENGINE2 write message in fragments
SQDS001I events: 1700000 avg:2
SQDS003I < 2 : 1139 ( 0.07%)
SQDS003I < 3 : 1698861 ( 99.93%) *******************
SQDS000I -----------------
SQDS004I CPU time to collect netstats: 00:00:00.077433
SQDT005I End speedtest elapsed 00:00:17.672941 (91.7361 MiB/s) writes:1703304 retries:3303 timeouts:0 for cdc:////ENGINE2 SQD0000I 2024-07-05 11:57:06
SQDT007I Diagnostic message received at 2024-07-05 11:57:06 -05:00
SQDT005I Start speedtest 1700000 1000-byte records (1.58325 GiB) for cdc:////ENGINE2
SQDT007I Diagnostic message received at 2024-07-05 11:57:24 -05:00
SQDT005I End speedtest elapsed 00:00:17.672941 (91.7361 MiB/s) writes:1703304 retries:3303 timeouts:0 for cdc:////ENGINE2