Date: Sun, 11 Dec 2022 01:22:46 -0700 From: Warner Losh <imp@bsdimp.com> To: Artem Kuchin <artemkuchin76@gmail.com> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: Everchanging bytes at the end of mirror disks Message-ID: <CANCZdfrO4M49i_WdidJUujQoJH1pAooTfxFtVjrNLU77EseH7Q@mail.gmail.com> In-Reply-To: <85c5a64c-915e-d790-e617-c94f3fb7cd9a@gmail.com> References: <85c5a64c-915e-d790-e617-c94f3fb7cd9a@gmail.com>
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--00000000000022b48b05ef89183d Content-Type: text/plain; charset="UTF-8" On Sat, Dec 10, 2022, 11:52 PM Artem Kuchin <artemkuchin76@gmail.com> wrote: > Hello! > > I am writing a small utility for myseld and part of it is comparing > gmirror disks. After running some tests i realized that some bytes at > the very end of disks are constantly changing. > The last sector has metadata about the mirror and about the mirror element. It's this latter data that differs. Warner For example to runs from the compator: > > Difference between /dev/ada0p3 [26,0x1A] and /dev/ada1p3 [95,0x5F] at > position 495812794495 > Difference between /dev/ada0p3 [217,0xD9] and /dev/ada1p3 [107,0x6B] at > position 495812794496 > Difference between /dev/ada0p3 [151,0x97] and /dev/ada1p3 [0,0x0] at > position 495812794497 > Difference between /dev/ada0p3 [180,0xB4] and /dev/ada1p3 [64,0x40] at > position 495812794498 > Difference between /dev/ada0p3 [96,0x60] and /dev/ada1p3 [126,0x7E] at > position 495812794499 > Difference between /dev/ada0p3 [89,0x59] and /dev/ada1p3 [239,0xEF] at > position 495812794500 > Difference between /dev/ada0p3 [234,0xEA] and /dev/ada1p3 [93,0x5D] at > position 495812794501 > Difference between /dev/ada0p3 [166,0xA6] and /dev/ada1p3 [76,0x4C] at > position 495812794502 > > Difference between /dev/ada0p3 [185,0xB9] and /dev/ada1p3 [233,0xE9] at > position 495812794495 > Difference between /dev/ada0p3 [145,0x91] and /dev/ada1p3 [2,0x2] at > position 495812794496 > Difference between /dev/ada0p3 [105,0x69] and /dev/ada1p3 [3,0x3] at > position 495812794497 > Difference between /dev/ada0p3 [55,0x37] and /dev/ada1p3 [166,0xA6] at > position 495812794498 > Difference between /dev/ada0p3 [23,0x17] and /dev/ada1p3 [99,0x63] at > position 495812794499 > Difference between /dev/ada0p3 [35,0x23] and /dev/ada1p3 [144,0x90] at > position 495812794500 > Difference between /dev/ada0p3 [118,0x76] and /dev/ada1p3 [212,0xD4] at > position 495812794501 > Difference between /dev/ada0p3 [30,0x1E] and /dev/ada1p3 [149,0x95] at > position 495812794502 > > End of disk is 495812794880, so, the last changing bytes if 378 bytes > before the end. > > I am most likely missing some information about FS/mirror organization. > Below is the filesystem configuration. > > However, if there a part which changes on both disks independently how > do i get its offset and size, > > so i will not compare it. Thank you. > > > # gmirror status > Name Status Components > mirror/swap COMPLETE ada0p2 (ACTIVE) > ada1p2 (ACTIVE) > mirror/root COMPLETE ada0p3 (ACTIVE) > ada1p3 (ACTIVE) > > # gpart show > => 34 976773101 ada0 GPT (466G) > 34 128 1 freebsd-boot (64K) > 162 8388608 2 freebsd-swap (4.0G) > 8388770 968384365 3 freebsd-ufs (462G) > > => 34 976773101 ada1 GPT (466G) > 34 128 1 freebsd-boot (64K) > 162 8388608 2 freebsd-swap (4.0G) > 8388770 968384365 3 freebsd-ufs (462G) > > > > > > --00000000000022b48b05ef89183d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"auto"><div><br><br><div class=3D"gmail_quote"><div dir=3D"ltr" = class=3D"gmail_attr">On Sat, Dec 10, 2022, 11:52 PM Artem Kuchin <<a hre= f=3D"mailto:artemkuchin76@gmail.com">artemkuchin76@gmail.com</a>> wrote:= <br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord= er-left:1px #ccc solid;padding-left:1ex">Hello!<br> <br> I am writing a small utility for myseld and part of it is comparing <br> gmirror disks. After running some tests i realized that some bytes at <br> the very end of disks are constantly changing.<br></blockquote></div></div>= <div dir=3D"auto"><br></div><div dir=3D"auto">The last sector has metadata = about the mirror and about the mirror element.=C2=A0 It's this latter d= ata that differs.</div><div dir=3D"auto"><br></div><div dir=3D"auto">Warner= </div><div dir=3D"auto"><br></div><div dir=3D"auto"><br></div><div dir=3D"a= uto"><div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"= margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> For example to runs from the compator:<br> <br> Difference between /dev/ada0p3 [26,0x1A]=C2=A0 and /dev/ada1p3 [95,0x5F] at= <br> position 495812794495<br> Difference between /dev/ada0p3 [217,0xD9]=C2=A0 and /dev/ada1p3 [107,0x6B] = at <br> position 495812794496<br> Difference between /dev/ada0p3 [151,0x97]=C2=A0 and /dev/ada1p3 [0,0x0] at = <br> position 495812794497<br> Difference between /dev/ada0p3 [180,0xB4]=C2=A0 and /dev/ada1p3 [64,0x40] a= t <br> position 495812794498<br> Difference between /dev/ada0p3 [96,0x60]=C2=A0 and /dev/ada1p3 [126,0x7E] a= t <br> position 495812794499<br> Difference between /dev/ada0p3 [89,0x59]=C2=A0 and /dev/ada1p3 [239,0xEF] a= t <br> position 495812794500<br> Difference between /dev/ada0p3 [234,0xEA]=C2=A0 and /dev/ada1p3 [93,0x5D] a= t <br> position 495812794501<br> Difference between /dev/ada0p3 [166,0xA6]=C2=A0 and /dev/ada1p3 [76,0x4C] a= t <br> position 495812794502<br> <br> Difference between /dev/ada0p3 [185,0xB9]=C2=A0 and /dev/ada1p3 [233,0xE9] = at <br> position 495812794495<br> Difference between /dev/ada0p3 [145,0x91]=C2=A0 and /dev/ada1p3 [2,0x2] at = <br> position 495812794496<br> Difference between /dev/ada0p3 [105,0x69]=C2=A0 and /dev/ada1p3 [3,0x3] at = <br> position 495812794497<br> Difference between /dev/ada0p3 [55,0x37]=C2=A0 and /dev/ada1p3 [166,0xA6] a= t <br> position 495812794498<br> Difference between /dev/ada0p3 [23,0x17]=C2=A0 and /dev/ada1p3 [99,0x63] at= <br> position 495812794499<br> Difference between /dev/ada0p3 [35,0x23]=C2=A0 and /dev/ada1p3 [144,0x90] a= t <br> position 495812794500<br> Difference between /dev/ada0p3 [118,0x76]=C2=A0 and /dev/ada1p3 [212,0xD4] = at <br> position 495812794501<br> Difference between /dev/ada0p3 [30,0x1E]=C2=A0 and /dev/ada1p3 [149,0x95] a= t <br> position 495812794502<br> <br> End of disk is 495812794880, so, the last changing bytes if 378 bytes <br> before the end.<br> <br> I am most likely missing some information about FS/mirror organization. <br= > Below is the filesystem configuration.<br> <br> However, if there a part which changes on both disks independently how <br> do i get its offset and size,<br> <br> so i will not compare it.=C2=A0 Thank you.<br> <br> <br> # gmirror status<br> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Name=C2=A0=C2=A0=C2=A0 Status=C2= =A0 Components<br> mirror/swap=C2=A0 COMPLETE=C2=A0 ada0p2 (ACTIVE)<br> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ada1p2 (ACT= IVE)<br> mirror/root=C2=A0 COMPLETE=C2=A0 ada0p3 (ACTIVE)<br> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ada1p3 (ACT= IVE)<br> <br> # gpart show<br> =3D>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 34=C2=A0 976773101=C2=A0 ada0= =C2=A0 GPT=C2=A0 (466G)<br> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 34=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 128=C2=A0=C2=A0=C2=A0=C2=A0 1=C2=A0 freebsd-boot= =C2=A0 (64K)<br> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 162=C2=A0=C2=A0=C2=A0 8388= 608=C2=A0=C2=A0=C2=A0=C2=A0 2=C2=A0 freebsd-swap=C2=A0 (4.0G)<br> =C2=A0=C2=A0=C2=A0=C2=A0 8388770=C2=A0 968384365=C2=A0=C2=A0=C2=A0=C2=A0 3= =C2=A0 freebsd-ufs=C2=A0 (462G)<br> <br> =3D>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 34=C2=A0 976773101=C2=A0 ada1= =C2=A0 GPT=C2=A0 (466G)<br> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 34=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 128=C2=A0=C2=A0=C2=A0=C2=A0 1=C2=A0 freebsd-boot= =C2=A0 (64K)<br> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 162=C2=A0=C2=A0=C2=A0 8388= 608=C2=A0=C2=A0=C2=A0=C2=A0 2=C2=A0 freebsd-swap=C2=A0 (4.0G)<br> =C2=A0=C2=A0=C2=A0=C2=A0 8388770=C2=A0 968384365=C2=A0=C2=A0=C2=A0=C2=A0 3= =C2=A0 freebsd-ufs=C2=A0 (462G)<br> <br> <br> <br> <br> <br> </blockquote></div></div></div> --00000000000022b48b05ef89183d--
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