Does power cuts ruin my OS?

Discussion in 'macOS' started by MacBH928, Aug 27, 2013.

  1. MacBH928 macrumors 68020

    MacBH928

    Joined:
    May 17, 2008
    #1
    I recently had few power cuts on my macbook because the battery is not giving me correct indications (It shut down while it said there was still %10+ battery)

    I wonder if those power shut downs can ruin my computer? I remember I had an iMac (lamp) that got the power cut of few times then it was not able to start. I had to use DiskWarrior to fix it.

    My macbook runs fine now but I wonder if there is any procedures I should follow to protect myself
     
  2. Shrink macrumors G3

    Shrink

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    Feb 26, 2011
    Location:
    New England, USA
    #2
    It's my understanding that the Mac shuts down automatically at that percentage.

    One procedure you might follow is to start charging your computer before it reaches shut down battery level.
     
  3. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #3
    No, interruptions in AC power don't harm your computer. It's the same as if you unplug it. It simply switches to battery power. The fact that it shuts down while showing 10% charge is attributable to the fact that the battery charge remaining is an ever-changing estimate, based on power demands at any point in time. The reading is not entirely accurate. You didn't mention what exact model MacBook you have, or whether it has a removable or built-in battery.

    The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.
     
  4. old-wiz macrumors G3

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    Mar 26, 2008
    Location:
    West Suburban Boston Ma
    #4
    Mains power outages on a desktop (iMac-like) can result in a corrupt disk if the power outage happens during a disk write. For a desktop I use a UPS.

    Mains power outages on a laptop aren't as much of a problem as long as battery remains. If the battery indicator is wrong, I would expect the system will do at least some flushing to make sure the disk will be OK when you restore power.
     
  5. MacBH928 thread starter macrumors 68020

    MacBH928

    Joined:
    May 17, 2008
    #5
    My battery died on me while using the macbook , how is that different from power outage on a desktop mac?


    I have a late 2008 macbook and the battery is removable last I checked.


    Also I am not worried about my battery but I am worried what would happen to my computer if it was cut out of power suddenly.

    @old-wiz

    how to fix a corrupted disk?
     
  6. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #6
    When is the last time you calibrated your battery? If you haven't calibrated recently, that may improve the accuracy of the readings. Also, how many cycles are on the battery and what is the health (maximum capacity)?

    If you're not already doing so, use iStat Pro (free) or iStat Menus ($16) to get accurate readings of battery health and cycles and computer uptime, among many other things. A forum member has posted a copy of iStat Pro that has been "tweaked" to enhance compatibility with Mountain Lion. You can download it here.

    For instructions on calibrating, see the CALIBRATION section of the Apple Notebook Battery FAQ I posted earlier.
     
  7. benwiggy macrumors 68020

    Joined:
    Jun 15, 2012
    #7
    Your laptop is designed to cope with running out of power from the battery. It has systems in place to save what you were doing and power down gracefully.

    Your desktop Mac relies on the power cable, and does not expect interruptions to that supply.
     
  8. old-wiz macrumors G3

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    #8
    Desktop does not have a battery to keep the system running long enough to clan up.

    To fix a corrupted disk, use something like Disk Warrior
     
  9. MacBH928 thread starter macrumors 68020

    MacBH928

    Joined:
    May 17, 2008
    #9
    @GGJStudios

    Thanks for your care to reply with help. I do have iStat pro and it says my battery's health is 66% and 198 cycles. I used to calibrate my battery once each month but I didn't do it for few months now. Its a long processes and my computer got old , its already past 4 years of use (Amazing yet very capable like new, even though I did upgrade the RAM from 2 to 6 and the HDD from 160GB->500).


    @old-wiz

    Ugghh...Disk Warrior is very expensive for a one time use product.


    @benwiggy
    Thanks for the tip. Apple should build in similar functions in the desktops
     
  10. old-wiz macrumors G3

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    West Suburban Boston Ma
    #10
    to do so would require a battery in the iMac/mini/MacPro, which would add to the cost and weight. Lots of times, losing power does not cause a problem, but it's rare for disk corruption to happen.
     
  11. Big-TDI-Guy macrumors 68030

    Big-TDI-Guy

    Joined:
    Jan 11, 2007
    #11
    Not quite.

    Assuming the battery health / charge indicator were somewhat accurate - what you said is usually true. However the OP indicated that the power indicator was way off from actual charge levels. In this case, the computer, thinking it has enough time to shut down, will begin, only to have power cut out unexpectedly before it has. This CAN result in corrupted / lost data.

    So to the OP - calibrate your battery monitor, and/or replace the battery just in case.
     
  12. MacBH928 thread starter macrumors 68020

    MacBH928

    Joined:
    May 17, 2008
    #12
    @Big-TDI

    thanks for the tip. I am more worried about my hard-drive being corrupted than the macbook's battery. I am surprised only DiskWarrior can fix this issue. Its a very expensive fix, a $100 one!
     
  13. MacBH928 thread starter macrumors 68020

    MacBH928

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    May 17, 2008
    #13
    If Apple can create something as light as the macbook air I am sure they can find a way to install a light battery into an iMac which sits on the desk for most of its lifetime.
     
  14. ElectricSheep macrumors 6502

    ElectricSheep

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    Location:
    Wilmington, DE
    #14
    Your old lamp-shade iMac G4 was introduced before journaling was a standard features in HFS+. This made corruption of the filesystem during sudden power-loss much more likely.

    These days, there are a few protections measures that prevent catastrophic damage or corruption to the disk.

    Journaling features of the filesystem (now on by default in all standard MacOS X installations) log the changes to be made to a filesystem to a special journaling area before actually committing those changes. It is only when the changes are successfully written to disk that the journal is cleared. If, for whatever reason, the write operation is interrupted before it can complete, all the system has to do is replay the journal to guarantee consistency.

    Modern hard drives have an emergency retract feature that parks the read/write head in the even of sudden external power loss. This is very important, as one of the worst things that can happen to a disk is physical contact of the head with the surface of the platter.

    These two features combined help prevent corruption of the disk in the event of external power loss. However, this will not protect you from other potential disasters, including user error. Always have a backup system in place.
     
  15. old-wiz macrumors G3

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    Mar 26, 2008
    Location:
    West Suburban Boston Ma
    #15
    I always preach you should have more than one backup of your system. I much prefer clone backups, but Time Machine is a workable option.

    It is amazing how many people start threads about "deleted xxxx files..no backup...HELP..." then rant about how their data was super important and they will die without the files, but don't take the time to make a backup, not even just the important files.

    Regardless of how power failures occur or how often, the drives, be they mechanical or SSD, can fail, period. Even if the system has code to flush the disk before power is gone, it may still fail.
     
  16. MacBH928 thread starter macrumors 68020

    MacBH928

    Joined:
    May 17, 2008
    #16
    Thanks for clearing that ElectricSheep

    I can be wrong but, do power failures over time slowly corrupts data until we get to a point where an HDD will not boot?

    because if this is so , then creating a backup from an HDD that had sudden loss of power, will create a partially corrupted back up. Am I correct?



    btw, what is a user error?


    @Old-wiz

    thanks . I backup around once a month. I have a laptop and having to connect the HDD daily and do a back is just not convenient . Plus I am afraid the constant reading and writing from-to HDDs might increase the chances of a failed HDD.
     
  17. LightningIceFox, Sep 1, 2013
    Last edited: Sep 1, 2013

    LightningIceFox macrumors newbie

    LightningIceFox

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  18. Big-TDI-Guy macrumors 68030

    Big-TDI-Guy

    Joined:
    Jan 11, 2007
    #18
    Funny story here... Just last week someone cut power without shutting down the computers first. One of them happened to be a laptop without a battery - while not entirely sure what aspect of the power failure did this - the computer (upon reboot) dies due to a logic board hardware failure, OS, RAM, and HDD all swapped without any change.

    It seems that something in the power management decided enough was enough.

    The odd thing here, the computer was on a uninterruptible power supply - which was a professional rack-mount system. It likely kept the laptop going for at least an hour, before the UPS batteries died off. So with the UPS in the loop - a voltage spike seems very unlikely, as it has built in line conditioning / protection for such things. So it was likely the abrupt power-off that caused the hardware failure.
     

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