This does not make sense to me:
> >> dd if=/dev/zero of=xx bs=1G count=1
> >>
> >> reports 2.6 GB (expected)
IMO ~ 1GB is expected, not 2.6:

$ dd if=/dev/zero of=xx bs=1G count=1
1+0 Datensätze ein
1+0 Datensätze aus
1073741824 Bytes (1,1 GB, 1,0 GiB) kopiert, 0,617959 s, 1,7 GB/s

Nik

Anno domini 2022 Thu, 23 Jun 14:27:59 +0200
Radisson via Dng scripsit:
> Its a normal HD i guess 4096 is ok,
> but i do not think that this matters.
>
>
> Am 23.06.22 um 13:11 schrieb Rich W:
> > Hi,
> >
> > A blocksize of 1G seems extreme.
> > What is the optimal blocksize of the output device?
> >
> > Cheers,
> > -Rich
> >
> >
> > On Thu, Jun 23, 2022, 4:52 AM Radisson via Dng <dng@???> wrote:
> >
> >> Hi list,
> >> i found a strange ext4 (?) effect.
> >>
> >> when i write to a disk:
> >> dd if=/dev/zero of=xx bs=1G count=1
> >>
> >> reports 2.6 GB (expected)
> >> doing again speed drops to 200MB.
> >>
> >> removing xx restores old speed.
> >>
> >> I ask the net and it seems that the effect is there
> >> since kernel 2.6. I found the explainations a bit confusing.
> >>
> >> does anyone know more ?
> >>
> >> note: i was analysing a performace issue for mysql and i am
> >> not sure if that problems matters outside tests.
> >>
> >> re
> >> rp
> >>
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> >>
> >
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