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Date:      Sun, 12 Jan 2025 14:17:51 -0700
From:      Alan Somers <asomers@freebsd.org>
To:        Cedric Blancher <cedric.blancher@gmail.com>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: WRITE_SAME support in FreeBSD nfsd NFSv4.1 mode?
Message-ID:  <CAOtMX2jVjMsDdE_E=kZg2OHUbhq=XzRuu1YEowyQXkyg%2Bx7qXg@mail.gmail.com>
In-Reply-To: <CALXu0UcP5WR_gV000akarzDxGap70jJwNaf7_BgKgVVU0S2bzg@mail.gmail.com>
References:  <CAAvCNcD1CziGxmgyzyWix5ADsDXRpkbFUM32H9nEji9kR%2BVc-Q@mail.gmail.com> <CAOtMX2i29F8NU493v81ggsdcprr7iifuD1aivaxsULxZrYt1tA@mail.gmail.com> <CALXu0UcP5WR_gV000akarzDxGap70jJwNaf7_BgKgVVU0S2bzg@mail.gmail.com>

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On Sun, Jan 12, 2025 at 12:23=E2=80=AFAM Cedric Blancher
<cedric.blancher@gmail.com> wrote:
>
> On Fri, 10 Jan 2025 at 16:02, Alan Somers <asomers@freebsd.org> wrote:
> >
> > On Thu, Jan 9, 2025 at 5:31=E2=80=AFPM Dan Shelton <dan.f.shelton@gmail=
.com> wrote:
> > >
> > > Hello!
> > >
> > > Does FreeBSD nfsd support the WRITE_SAME request in NFSv4.1 mode?
> > >
> > > Dan
> > > --
> > > Dan Shelton - Cluster Specialist Win/Lin/Bsd
> >
> > Out of curiosity, what is your use case?
>
> As discussed in the linux-nfs@ list, is a typical "big data" and
> database accelerator, for example fast pattern fill (1 WRITE_SAME
> command over the write, compared to <n> commands with data block,
> where <n> is typically > 200 average), or just zero fill for blocks.
> It's basically reducing network traffic dramatically.
>
> Windows SMB 3.0 already supports that, and is a main selling point for
> M$ to keep database people on the W$ platform. They even added several
> Windows syscalls like
> https://learn.microsoft.com/en-us/windows/win32/api/winioctl/ni-winioctl-=
fsctl_set_zero_data
>
> Ced

I understand why WRITE SAME would greatly reduce network traffic
compared to writing the same data n times.  But my question is, what
real application requires that, where the data isn't simply all-zeros?
 Are there database operations that require writing the same non-zero
pattern to multiple blocks?



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