Thanks Satid. In case it might be useful to someone who finds this thread, I came up with a query to estimate the date when the system would reach 100% temp address utilization. This is based on the last IPL date (taken as the timestamp of QCTL subsystem starting up) and the current temp address percentage.
--Description: based on the start date of QCTL subsystem and the current temp address percentage, estimate the date when temp addresses would reach 100% causing a crash of the LPAR
SELECT CAST((A.TEMPORARY_ADDRESS_RATE)/(TIMESTAMPDIFF(16, CHAR(CURRENT TIMESTAMP - B.JOB_ACTIVE_TIME))) AS DEC(8,6)) AS TEMP_ADDRESS_PERCENT_PER_DAY,
(100-A.TEMPORARY_ADDRESS_RATE) AS TEMP_ADDRESS_PERCENT_REMAINING,
(100-A.TEMPORARY_ADDRESS_RATE) / ((A.TEMPORARY_ADDRESS_RATE)/(TIMESTAMPDIFF(16, CHAR(CURRENT TIMESTAMP - B.JOB_ACTIVE_TIME)))) AS DAYS_UNTIL_100PERCENT,
CURRENT DATE + ((100-A.TEMPORARY_ADDRESS_RATE) / ((A.TEMPORARY_ADDRESS_RATE)/(TIMESTAMPDIFF(16, CHAR(CURRENT TIMESTAMP - B.JOB_ACTIVE_TIME))))) DAYS AS PROJECTED_CRASH_DATE
FROM QSYS2.SYSTEM_STATUS_INFO_BASIC A
CROSS JOIN
TABLE ( QSYS2.ACTIVE_JOB_INFO( JOB_NAME_FILTER => 'QCTL', DETAILED_INFO => 'WORK') ) B
WHERE JOB_TYPE = 'SBS';
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Steven Riedmueller Certified IBM i Admin - Speaker, Mentor, and Advocate
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Original Message:
Sent: Sat June 24, 2023 10:32 PM
From: Satid Singkorapoom
Subject: How often to IPL?
Kent Milligan has just made a DB2 for i blog post sharing his insight on IPL, DB2 Plan Cache and autonomic index (Maintained temp index - MTI) with a focus on SQL workload performance after an IPL. One useful information is on the new MTI_INFO service that helps us be aware of all existing autonomic indexes to help us make a decision to create them (not necessarily all) as the normal indexes to prevent what he calls "Monday Blues" :-) Read it here : https://db2ibmi.blogspot.com/2023/06/the-amazing-disappearing-plan-cache.html
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Education is not the learning of facts but the training of the mind to think. -- Albert Einstein.
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Satid S.
Original Message:
Sent: Wed May 24, 2023 09:12 AM
From: Steven Riedmueller
Subject: How often to IPL?
Hi Rob, that was me. :) And yes indeed after ~6 months LPAR uptime I see 53% temp addresses used. Ideally I'd like to be applying PTFs (and IPLing) 4x per year, and I'd settle for 2x per year. In reality I get 1 outage per year for my main LPAR, which is where temp addresses become a concern.
We also have an issue with very high "native full opens".
Unfortunately it feels like I'm screaming into the void when I try to raise either of these concerns.
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Steven Riedmueller Certified IBM i Admin - Speaker, Mentor, and Advocate
Original Message:
Sent: Wed May 24, 2023 07:43 AM
From: Robert Berendt
Subject: How often to IPL?
Oddly enough I got a reply on another forum that there is someone who still has an issue with "% temp addresses" on DSPSYSSTS. I haven't had an issue with that since CISC days. He has to IPL because of that. It hasn't been a big enough issue to pursue more vigorously.
Remember, "% temp addresses" is NOT temporary space. Temporary space is something you can research with some of the newer IBM i Services.
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Robert Berendt IBMChampion
Original Message:
Sent: Tue May 23, 2023 02:31 PM
From: Robert Berendt
Subject: How often to IPL?
A recent discussion on LinkedIn discouraged IPLing frequently. And they have a good point as each IPL resets your query optimizer and throws out all temporary indexes. The catch was basically you should reduce IPLs for PTF's, etc.
Here's the catch though: How often should you put on the PTF's? I think we're better than most shops because we put on the latest cume and groups on a quarterly basis. And there's always those shops that want to be some lengthy amount of time behind. But how do you explain to your stakeholders that you were notified that you were potentially exposed because you don't have this Java group ptf on, or you don't have this level of firmware on, or this Hiper group on? Do you tell them:
- "I know of the risk that we could lose a bunch of confidential information but what if there's a flawed PTF and it causes issues?"
- "I know that IBM found an issue with the current level we're at and issued a fixing PTF but what if that fixing PTF causes issues?"
- "We've been on this level for two years now and nothing has happened so why fix what isn't broken?"
We're finding out that newer certification levels are requiring you to put patches on much more frequently than most people do. And, frankly, it takes less disruptive time to patch an IBM Power system than it does a Windows Server.
If there's an incident, and management finds out that you were notified by IBM notifications and you didn't put on the patch, are you going under the bus?
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Robert Berendt IBMChampion
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