tune2fs -m "reserved space?"

[Justin Conover]

On 10/4/05, Justin Conover <justin.conover at gmail.com> wrote:
>
>
>
> On 10/4/05, Arjan van de Ven <arjanv at redhat.com> wrote:
>
> > On Tue, 2005-10-04 at 12:24 -0500, Justin Conover wrote:
> > > tune2fs
> > > -m reserved-blocks-percentage
> > > -r reserved-blocks-count
> > >
> > > If what I have read is correct, -m by default uses 5% of the disk
> > > space for "reserved root use" On my server at home with a /home of
> > > 1TB thats about 50GB of wasted space.
> > >
> > > Is this reserved space actually used by ANYTHING? Like LVM, some kind
> > > of fragmentation?
> >
> > well for emergency root stuff; logging in without any disk space is
> > hard; lots of stuff wants to make temporary files etc.
> >
> > but your second point it true too: most filesystems (ext3 but most
> > others) start to fragment like hell if they go over about 95% full.
> >
> > Think of it this way: if you have half your disk empty, the filesystem
> > can do a proper job of finding non-fragmented space.
> > If only 0.0001% is free, it has almost no freedom of choice, resulting
> > in "you get it in whatever order some things become free".
> > Those are sort of extremes; there's been a bunch of research and the
> > outcome was that 5% free seems to be sort of the turning point in this
> > respect.
> >
> > I suspect that research predates the Tb sized volumes, so I don't know
> > if it maybe is 1% on such volumes, but then again to some extend the
> > freedom needed will scale with the FS size
> >
> >
> > -----BEGIN PGP SIGNATURE-----
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> >
> > iD8DBQBDQsEXpv2rCoFn+CIRAvUXAJ0SH+Pc9eXpinhuBGZ+DM4r5wTCtgCgi+7B
> > hxT89EtumMwOF13z0l0KP9Q=
> > =C5z1
> > -----END PGP SIGNATURE-----
>
>
> This is a vg on the 1TB a 625GB slice, If i'm reading this correctly than
> I have about 32GB "free" space right?
>

I lied, thats a 500GB slice I had just looked at the vg allocated space :)

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup01-LogVol00
493G 306G 162G 66% /home/amy
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