Find the Busiest Hour in the Day for I/O
Jim_Knicely
- Select Field - Administrator
The IO_USAGE system table provides disk I/O bandwidth usage history for the system. You can query it to find out interesting IO statistics like which hour of the day has the most IO usage on your Vertica cluster!
Example:
dbadmin=> SELECT *
dbadmin-> FROM (SELECT "HOUR", "Total IO (GB)", "Read IO (GB)", "Write IO (GB)"
dbadmin(> FROM (SELECT MIN(TRUNC(start_time)) start_time,
dbadmin(> DATE_TRUNC('hour', start_time) as "HOUR",
dbadmin(> (SUM(read_kbytes_per_sec) + SUM(written_kbytes_per_sec)) * 60/1024/1024 as "Total IO (GB)",
dbadmin(> SUM(read_kbytes_per_sec) * 60/1024/1024 as "Read IO (GB)",
dbadmin(> SUM(written_kbytes_per_sec) * 60/1024/1024 as "Write IO (GB)"
dbadmin(> FROM v_monitor.io_usage
dbadmin(> GROUP BY 2) foo
dbadmin(> WHERE start_time >= TRUNC(SYSDATE) - 5 -- LAST 5 DAYS!
dbadmin(> LIMIT 1 OVER (PARTITION BY start_time ORDER BY start_time, "Total IO (GB)" DESC)) foo2
dbadmin-> ORDER BY "HOUR" DESC;
HOUR | Total IO (GB) | Read IO (GB) | Write IO (GB)
---------------------+------------------+---------------------+------------------
2019-08-02 10:00:00 | 7.31542510986328 | 1.28464279174805 | 6.03078231811523
2019-08-01 23:00:00 | 13.6195484161377 | 10.5460218429565 | 3.07352657318115
2019-07-31 23:00:00 | 13.6010026931763 | 10.5195688247681 | 3.0814338684082
2019-07-30 12:00:00 | 104.669023132324 | 6.8077428817749 | 97.8612802505493
2019-07-29 14:00:00 | 1.92557315826416 | 0.00724811553955078 | 1.91832504272461
(5 rows)
Helpful Link:
https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/SQLReferenceManual/SystemTables/MONITOR/IO_USAGE.htm
Have fun!
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