As400 Power down

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AS/400
I have a I series model 270. The machine never powers down and hasn't been powered cycled in 6 months. Should these machines be power cycled or powered down over the weekend possibly?
ASKED: April 8, 2006  11:28 AM
UPDATED: December 3, 2009  7:37 AM

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there are different schools of thought on this subject. We do a power down during our backup cycles every Saturday evening at 1am. Others will do this monthly. Others less often. With more real time 24×7 requirements, the simple power down and up is becoming harder to do. I am of the opinion that it should be done periodically and 6 months is too long. I look forward to what others have to say on this subject.

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My opinion is that it depends on whether you have a hardware maintenance agreement or not and how much time you can afford to be down.

I prefer an actual power cycle. The system should be down long enough for components to cool near to room temperature before powering back up. This provides a tolerance test that isn’t available any other way. It also provides simple exercise of moving components such as disk arms — they can all fully move to their at rest positions and move away from them.

For disk drives (and arms), the power cycle can influence the amount of stiction that may grow over time from aging lubricants. If stiction is becoming a problem, it can become a major problem at the wrong time. Unfortunately, sometimes you simply have to shut machines down. Maybe you have scheduled maintenance to upgrade some controllers. Or maybe there’s a regional power outage. For whatever reason, you have the system powered off and you have a definite time you intend to have it powered back up.

That’s not the moment to discover that a drive isn’t going to power back up.

So, when it’s reasonable, I have full power cycles — including cool-down — at regular intervals. If a power related failure is going to happen, I want to minimize the chance of it happening when some unrelated other major issue is happening.

Tom

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  • astradyne
    I have a 150 that I use at home and that usually only gets powered down when a) there's a power cut or b) I'm working on the electrics in the house and pull the fuse. Being only a 150 the IPL is relatively slow so I tend to avoid having to do one. At the last three companies I worked for we only ever did an IPL as part of a system (software, hardware or application) upgrade anyway and never experienced any problems. As DaddyCOZ said, running 24x7 operations makes it very difficult to find windows of opportunity to bounce the system. Personally, I wouldn't worry about it too much. If you have the opportunity to perform regular power downs and are happy to do so then do. On the other hand, if you don't have the opportunities because of operation times then limit them to upgrades - I don't think you'll have any problems.
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  • EgamiEsrever
    Generally speaking you only need to power down when a PTF install requires it or on the odd occassion you need to for support reasons from IBM. These aren't Windows boxes, so if the machine isn't indicating it needs one then you're fine not doing it. Regardless of platform...it's easier on hardware when you can leave a machine just running. Have a good day!
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  • Qsecofr13
    I won't worry about IPL, too. Just do it as and when you need to. There is no need to do one just for the sake of doing one!
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  • Monitor17
    We have an old system that was running several months without recycling. After a shutdown becuase of power maintenance, one of the disks did not start again (unfortunately the load source). The Engineer removed it, knocked it on the table, built it in again, and ... it worked !!!!
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  • Wmarshment
    Whilst I agree with all of the comments so far, there is one thing to look out for on the WRKSYSSTS screen, the % perm addresses & temp addresses, if they start to get ( I have always said where I have worked above 20 % ) a little high, its a good time to do an IPL. The system performance will improve. I think IBM have a figure thats a good guideline but I can not remember what it was Plus the longer between IPLs the longer an IPL will take. Regards Bill
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  • Verl810
    We use the recommendation from Mike Dawson?s ?The AS/400 Owner?s Manual? where he suggests 6 time you ?need? to IPL. They are after a power failure or abend, after installing certain types of PTFs, after installing a licensed-program from IBM, at IBM support?s direction, when address usage reaches 90% (we use 85%) and when auxiliary storage reaches 95% (we use 85% here too). With the current generation of AS/400 the IPL may not be required at these times, but performance improvements and peace of mind are also benefits of following these recommendations. Best regards, Verl810
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  • ManxAnts
    I am not going to say don't bother IPLing, its not necessary. It really depends on how much you are using your machine, and whether you are experiencing issues with it. If you undertake to delete objects as part of a regular process, or you are updating objects, you will find that the temporary and permanent addresses in use by the machine will increase. (You can check using WRKSYSSTS). As you don't have direct control of the disk, these effectively are the pointers of where data resides, and if it is moved you could find the chain to get to your record is quite lengthy. By IPLing the machine, you will reduce these to start/end positions of where the data resides at the time of the IPL. This results in a speed up of accesses. Additionally, you will find if you leave IPLs too long between doing them, the IPL itself will take longer. Therefore, the is a reason for doing a regular IPL. I could go into many other reasons as well, but these would be the main ones to think about. Regards ManxAnts
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  • DanTheDane
    Several replyes to your question, tells that system will run faster after an IPL, which is right. Luckyly you may run the cleaning procedures on request thus achieving the same 'tuning' result. Look into the STRCLNUP command (which is part of the QSTRUP-program which controlls the IPL). Also look into the STRDSKRGZ (Start Disk Reorganisation) command, which allows you to run disk-reorg 'on the fly' while running production. Thus you may leave your system as a 24x7 system - it is build for that. Regarding disks that wont start again - this phenomenom is (..to my knowledge) only known with older disks. Enter the command-names, press F1 and read the help text. Good luck.
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  • DonKennedy
    Lets distinguish 2 different things. Power down and re-IPL. The re-IPL uses the PWRDWNSYS RESTART(*YES) command to re-IPL without actually powering off anything. That IMHO should be done periodically, at least once a month. We do ours every Saturday at midnight to take to a restricted state to do backups and clean up temp storage, etc (as mentioned in previous posts). As for a true POWER DOWN, PWRDWNSYS RESTART(*NO), it's only ever done when needed for hardware update/replacement purposes. That seems to be a good policy. There's no reason to actually turn the power off and on again unless absolutesly necessary. It can cause more problems than it would resolve. So which does the original poster really mean?
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  • DaddyCOZ
    I think DonKennedy makes a good point. I am pretty sure that everyone is talking about a pwrdwnsys restart(*yes). No one would really want to power down and then do a manual restart except in dire emergencies. Now, we can upgrade and replace disks hot so even many hardware upgrades do not need a power down without a restart.
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  • Rayne427
    Even though an AS/400 - System is meant to be run all of the time and never go down, in my experience, I have always set aside time to do an IPL. In my current position, we have set our system to IPL at 2:00AM on Monday mornings. This takes care of applying any PTF files loaded during the week and just sets the system up for the upcoming week with a "clean slate" so to say. In my previous position, we would IPL monthly. Basically, it is up to you. If you are in a position where you can set up an IPL to occur using the job scheduler, and it doesn't disrupt any production, I say do it. If you are a 24/7 operation like we are, get together with the people that would be affected the most and write a policy to get in an IPL at least once per month.
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  • Bamaro70
    Like most here have said, its not absolutely necessary but it is nice to do. If you have the time to do it, schedule a PWRDWNSYS RESTART(*YES) once a week or once a month. It will probably only take about 20 minutes.
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  • MrBothun
    I agree that it's better to keep the system running. It's also important to keep up with the OS and hardware fixes. Keeping current on your fixes does 2 things for you: 1. Keeps your system up to date, hopefully avoiding problems in the first place. 2. Reduces the production down time for problem determination if you do have a problem. Having regular weekend system down time makes it much easier to download and install fixes. Our shop is 24x7 and it takes an act of Congress to take our system down. Good Luck!
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  • USRPRF
    One thing the IPL benefits you is that every time the IPL is done, it'll also reset the 'unprotect storage used' (this is actually some amount of DASD size in ASP1 which cannot be cleared on-line). I believe it is a good thing to do - refresh system periodically. As our practice, we perform it every month.
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  • MDratwa
    The AS400 we run is usually running 24 x 7 x 365. The last 5 yrs, the only time that we powered off was when the cache battery needed to be replaced. This occurs about 13-15 months. The AS400 is running checks all of the time and will report if it finds something. Grant you they are run at different times, but my understanding (from the System 38 days and I assume it is true for AS400) that the only time that all of the checks are run together (and some only on power up) is when the system is powered up (from restart(*no)) You should be fine not worrying about powering down (or restart(*yes)) is to reset your addresses and/or some of the disk storage.
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