On Thursday 23 June 2022 at 15:41:21, Dr. Nikolaus Klepp via Dng wrote:

> 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

I agree with what you say, but I had the impression that Radisson was trying
to say that the transfer rate was 2.6 Gbps the first time, and 200 Mbps the
second time.


Antony.

> 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 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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