HMC

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  • 1.  HMC Restart Recommendation

    Posted Wed November 11, 2020 05:10 AM
    Hello All, 

    Simply and "easy" question.

    Do you have any recommendations on how often to reboot the HMCs?

    Thanks,

    Fernando

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    Fernando Plaza Vidaurre
    IBM i System Admin
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  • 2.  RE: HMC Restart Recommendation

    IBM Champion
    Posted Thu November 12, 2020 03:49 AM
    Fernando,

    Hi, we tend to monitor memory usage and then re-boot accordingly as we've seen issues with low memory affecting Frame firmware updates/upgrades in the past.

    So, for example, running monhmc -r mem and seeing the below would suggest we've 0.5GB "free" so might be time to re-boot.

    Every 4.0s: MONHmc mem Thu Nov 12 08:41:59 2020
    
    KiB Mem : 32919864 total, 477068 free, 20001772 used, 12441024 buff/cache​

    Regards, Steve

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    Steve Munday
    AIX, IBM i, PowerVM
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  • 3.  RE: HMC Restart Recommendation

    Posted Thu November 12, 2020 04:35 AM
    Thanks Steve, 

    Good tip!

    Fernando

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    Fernando Plaza Vidaurre
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  • 4.  RE: HMC Restart Recommendation

    IBM Champion
    Posted Wed November 18, 2020 01:01 PM

    Hi Fernando,

    I have several HMCs, my practice is:

    1. Always use the dual-HMC environment, at least for production, to avoid such problems.

    2. Old HMC hardware works not too good with new HMC software. It's obvious. it's officially not supported (?), but addding some extra OEM memory DIMMs may help.

    3. If you "feel" that your HMC became slower - reboot it!

    4. Configure the IMM interface at the HMC hardware server, it will help to reboot the hanged one.

    monhmc is the good tool, but I've practically never used it and don't worry about it.
    It's my practical view only.



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    Dmitry Mironov
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  • 5.  RE: HMC Restart Recommendation

    Posted Thu November 19, 2020 02:16 AM
    Hi Dmitry .. first thanks for your reply .. 

    We also have dual-HMC ...

    3. If you "feel" that your HMC became slower - reboot it! Is my recommendation too, but sometimes no time to reboot when you detect the HMC is slow ... 

    The tip of Steve Munday looks interesting with momhmc -r Mem

    Fernando



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    Fernando Plaza Vidaurre
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  • 6.  RE: HMC Restart Recommendation

    IBM Champion
    Posted Thu November 19, 2020 04:38 AM

    Fernando,

    Surely monhmc is a good advice, but in case you have no time to reboot - see "1": dual HMC.

    Anyway it's a very smart idea, you may achieve better fault prediction if intergrate it with your monitoring solution (Tivoli, HP, Zabbix or anything else):

    grant the necessary permission to the Monitoring, run the monhmc on schedule, alert on threshold.

    Use ssh keys to login to the HMC without password.



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    Dmitry Mironov
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