[wplug] Re: MD on atop of LVM (or LVM2's native RAID), instead of LVM on top of MD -- WAS: Install Question

Bryan J. Smith b.j.smith at ieee.org
Wed Jul 25 17:09:59 EDT 2007


On Wed, 2007-07-25 at 16:38 -0400, Drew from Zhrodague wrote:
> I have just the opposite experience, which has me choose to use 
> one big / partition.

BTW, don't take offense to anything I say, I'm a fully self-aware SOB.
We all have our own experiences.

But this does remain ...

> Whoa!  Whoa!  Whoa!
> Q:  What is the purpose of meta-data journaling?
> A:  _Mitigate_ the time it takes to put the filesystem into a
>     "clean" state.
> I stress the word "mitigate."  Why?
> Q:  Which is _better_ for ensuring a filesystem is consistent?
>   1.  Full fsck
>   2.  Full data journaling
>   3.  Meta data journaling
> A:  1, period -- journaling does _not_ guarantee consistency
> Almost as good:  2, with NVRAM as your full data journaling
> Journaling is _only_ "mitigating" the risk of an inconsistent
> filesystem.  _Only_ a full fsck _guarantees_ it.  ;)

Full fsck's _always_ guarantee filesystem consistency.
Journaling does _not_.  ;)


-- 
Bryan J. Smith         Professional, Technical Annoyance
mailto:b.j.smith at ieee.org   http://thebs413.blogspot.com
--------------------------------------------------------
        Fission Power:  An Inconvenient Solution



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