Date: Wed, 5 Oct 2022 15:41:13 -0600 From: Warner Losh <imp@bsdimp.com> To: Pau Amma <pauamma@gundo.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Block sizes for dd(1) to USB memory sticks (flash drives) for installers for FreeBSD Message-ID: <CANCZdfpUOxr3My-oR=aoZrLCKpJszdqHf9jCYLo7bSXAoxeQPw@mail.gmail.com> In-Reply-To: <3999539a33b13a2843ae50b5ba3c44fa@gundo.com> References: <1cede94a-c114-17fa-a81c-bb58c2b5879c@freebsd.org> <750a38c-2c86-a571-eb65-f63998b7649f@puchar.net> <3999539a33b13a2843ae50b5ba3c44fa@gundo.com>
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--0000000000003fefde05ea5070ad Content-Type: text/plain; charset="UTF-8" On Wed, Oct 5, 2022 at 6:10 AM Pau Amma <pauamma@gundo.com> wrote: > On 2022-10-03 08:26, Wojciech Puchar wrote: > >> <https://www.freebsd.org/releases/13.1R/announce/#_availability>; and > >> elsewhere: > >> > >> bs=1m > >> > >> Why so small? > > I've just checked. 128kB, 1MB and 4MB makes no noticable difference > > I remember someone in #freebsd (memory says debdrup) saying 128K is the > largest amount FreeBSD will write to a file or device as a single unit. maxphys used to be 128k. That changed in 13 to be 1MB (though it can be as large as 8MB). However, the maximum transfer size often is 256k or 512k for USB thumb drives and in the cases where it's less than 1MB, we'll do less. Warner --0000000000003fefde05ea5070ad Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote">= <div dir=3D"ltr" class=3D"gmail_attr">On Wed, Oct 5, 2022 at 6:10 AM Pau Am= ma <<a href=3D"mailto:pauamma@gundo.com">pauamma@gundo.com</a>> wrote= :<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.= 8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On 2022-10-03 = 08:26, Wojciech Puchar wrote:<br> >> <<a href=3D"https://www.freebsd.org/releases/13.1R/announce/#_a= vailability" rel=3D"noreferrer" target=3D"_blank">https://www.freebsd.org/r= eleases/13.1R/announce/#_availability</a>> and <br> >> elsewhere:<br> >> <br> >> bs=3D1m<br> >> <br> >> Why so small?<br> > I've just checked. 128kB, 1MB and 4MB makes no noticable differenc= e<br> <br> I remember someone in #freebsd (memory says debdrup) saying 128K is the <br= > largest amount FreeBSD will write to a file or device as a single unit.</bl= ockquote><div><br></div><div>maxphys used to be 128k. That changed in 13 to= be 1MB (though it can be as large</div><div>as 8MB).=C2=A0</div><div><br><= /div><div>However, the maximum transfer size often is 256k or 512k for USB = thumb drives</div><div>and in the cases where it's less than 1MB, we= 9;ll do less.</div><div><br></div><div>Warner</div></div></div> --0000000000003fefde05ea5070ad--
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