fsck is a standard unix process performed at startup - basically when
you write data to storage (ie disk or SSD), the OS caches a copy of
the data in RAM, and then fires up a background process to actually
store the data to storage. Similary, if you're using an old-fashioned
hard drive (which is slow), it has some inbuilt RAM that the data is
cached into to improve responsiveness.

The problem is if power goes down during that process, that data get
lost. So the OS will persist some markers in permanent storage to
indicate what it is about to to, and doesn't destroy the old data
until things are done. So fsck essentially cruises the storage media
looking for those markers, and fixes things back up to how they were
before you did the write. It also means that whilst not recommended,
hitting the power button on a unix/posix system very rarely causes
data loss, unlike in the very old days where the chance of completely
hosing your system was quite real.

Windows also does a similar strategy ever since the Windows NT code
was merged (ie from about Windows XP onwards). Before that Windows
(and MSDOS) persisted all data at write time, which was not only very
slow, but also completely hosed your system if the power goes down at a
crucial time.

Cheers

On Sun, Apr 12, 2026 at 07:01:57PM -0600, Gillian Densmore wrote:
> Greetings all,
> Basically I'm on Bazzite linux a atomic linux distro... . My question:
> Yesterday I checked for updates (if any) just as the power to my house had a
> hickup. After my computer restarted I saw a fewthings I'm just curious about.
> if someone can Eli5 as I am what you might say: kind of retarded.
> 
> Basically first a screen full text, a few automatic reboots more text and then
> a screen saying something like: Hey there: we actually fixed 99things. 
> Chatgpts (I suspect)--dubious answer is basically: oh that was probably fsk, 
> it
> runs by default on redhat to check ostree and keep your system sane and
> healthy, but because you have to..kind of like save states or worlds if this
> was the sims..
> Were I am curious anyone know how Atomic linux-> Bazzite does a pretty awesome
> job of self healing? 
> 
> 
> 

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Dr Russell Standish                    Phone 0425 253119 (mobile)
Principal, High Performance Coders     [email protected]
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