Date: Sun, 13 Nov 2022 22:03:15 +0300 From: Mehmet Erol Sanliturk <m.e.sanliturk@gmail.com> To: Bob Friesenhahn <bfriesen@simple.dallas.tx.us> Cc: Mark Saad <nonesuch@longcount.org>, freebsd-fs@freebsd.org Subject: Re: Odd behaviour of two identical ZFS servers mirroring via rsync Message-ID: <CAOgwaMueCqSiUd8FHuuHOo=q5aPrkGo3LaTTm8E0GBrDNiVv6A@mail.gmail.com> In-Reply-To: <alpine.GSO.2.20.2211131137020.7126@scrappy.simplesystems.org> References: <alpine.BSF.2.22.395.2211111709230.29479@mail0.time-domain.net> <CAOgwaMuoLQ9Er67Y%2B=q%2Bf9724v2WT3L5v5TZaRVXq%2B=1vEyJ%2BA@mail.gmail.com> <alpine.BSF.2.22.395.2211112008220.30520@mail0.time-domain.net> <alpine.GSO.2.20.2211121949060.7126@scrappy.simplesystems.org> <CAMXt9Nbr=7K6PELVGAPZ=-RiAfx=zp9iOoKyWdH=0H2=AiE52Q@mail.gmail.com> <alpine.GSO.2.20.2211131137020.7126@scrappy.simplesystems.org>
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On Sun, Nov 13, 2022 at 8:46 PM Bob Friesenhahn <
bfriesen@simple.dallas.tx.us> wrote:
> On Sun, 13 Nov 2022, Mark Saad wrote:
> >>
> > Bob are you saying when the target is zfs --inplace --no-whole-file hel=
ps
> > or just in general when you have
> > large files ? Also have you tried using --delete-during /
> --delete-after ?
>
> The '-inplace --no-whole-file' updates the file blocks if they have
> changed (comparing the orgin blocks with the existing mirror blocks)
> rather than creating a new copy of the file and moving it into place
> when it is complete. ZFS does not check if data content has been
> changed while it is being written so a write of the same data will
> result in a fresh allocation based on its Copy On Write ("COW")
> design. Writing a whole new file obviously significantly increases
> the number of blocks which are written. Requesting that rsync only
> write to the file for the blocks which have changed reduces the total
> number of blocks which get written.
>
> The above helps quite a lot when using snapshots since then fewer
> blocks are in the snapshots.
>
> I have never tried --delete-during so I can't comment on that.
>
> Bob
> --
> Bob Friesenhahn
> bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen=
/
> GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
> Public Key, http://www.simplesystems.org/users/bfriesen/public-key.tx=
t
>
>
More information on zfs and rsync :
https://www.google.com/search?q=3Duse+of+rsync+command+for+zfs+volumes&sxsr=
f=3DALiCzsZALxJWD--EizNVNAHl-u-j6BOndw%3A1668365903483&source=3Dhp&ei=3DTz5=
xY6XbGrCQxc8Plbyl8A0&iflsig=3DAJiK0e8AAAAAY3FMX56shwXahupzkNcfFLLhJJd0xL1U&=
ved=3D0ahUKEwjlvp6o66v7AhUwSPEDHRVeCd4Q4dUDCAc&uact=3D5&oq=3Duse+of+rsync+c=
ommand+for+zfs+volumes&gs_lcp=3DCgdnd3Mtd2l6EAMyBQgAEKIEOgQIIxAnOgsILhCABBD=
HARDRAzoFCAAQgAQ6CAguENQCEIAEOggILhCABBDUAjoFCC4QgAQ6CAgAEIAEEMsBOggILhCABB=
DLAToGCAAQFhAeOggIABAWEB4QDzoFCAAQhgM6BQghEKABOgQIIRAVOggIIRAWEB4QHToHCCEQo=
AEQClAAWI6bAmCtnQJoAHAAeACAAbkCiAHkLJIBCDAuMzUuMC4xmAEAoAEB&sclient=3Dgws-w=
iz
use of rsync command for zfs volumes
Mehmet Erol Sanliturk
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<div dir=3D"ltr"><div dir=3D"ltr"><div class=3D"gmail_default" style=3D"fon=
t-family:tahoma,sans-serif;font-size:large"><br></div></div><br><div class=
=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Sun, Nov 13, 2022=
at 8:46 PM Bob Friesenhahn <<a href=3D"mailto:bfriesen@simple.dallas.tx=
.us">bfriesen@simple.dallas.tx.us</a>> wrote:<br></div><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
b(204,204,204);padding-left:1ex">On Sun, 13 Nov 2022, Mark Saad wrote:<br>
>><br>
> Bob are you saying when the target is zfs --inplace --no-whole-file he=
lps<br>
> or just in general when you have<br>
> large files ?=C2=A0 Also have you tried using --delete-during / --dele=
te-after=C2=A0 ?<br>
<br>
The '-inplace --no-whole-file' updates the file blocks if they have=
<br>
changed (comparing the orgin blocks with the existing mirror blocks) <br>
rather than creating a new copy of the file and moving it into place <br>
when it is complete.=C2=A0 ZFS does not check if data content has been <br>
changed while it is being written so a write of the same data will <br>
result in a fresh allocation based on its Copy On Write ("COW") <=
br>
design.=C2=A0 Writing a whole new file obviously significantly increases <b=
r>
the number of blocks which are written.=C2=A0 Requesting that rsync only <b=
r>
write to the file for the blocks which have changed reduces the total <br>
number of blocks which get written.<br>
<br>
The above helps quite a lot when using snapshots since then fewer <br>
blocks are in the snapshots.<br>
<br>
I have never tried --delete-during so I can't comment on that.<br>
<br>
Bob<br>
-- <br>
Bob Friesenhahn<br>
<a href=3D"mailto:bfriesen@simple.dallas.tx.us" target=3D"_blank">bfriesen@=
simple.dallas.tx.us</a>, <a href=3D"http://www.simplesystems.org/users/bfri=
esen/" rel=3D"noreferrer" target=3D"_blank">http://www.simplesystems.org/us=
ers/bfriesen/</a><br>
GraphicsMagick Maintainer,=C2=A0 =C2=A0 <a href=3D"http://www.GraphicsMagic=
k.org/" rel=3D"noreferrer" target=3D"_blank">http://www.GraphicsMagick.org/=
</a><br>
Public Key,=C2=A0 =C2=A0 =C2=A0<a href=3D"http://www.simplesystems.org/user=
s/bfriesen/public-key.txt" rel=3D"noreferrer" target=3D"_blank">http://www.=
simplesystems.org/users/bfriesen/public-key.txt</a><br>
<br></blockquote><div><br></div><div><br></div><div><br></div><div><div sty=
le=3D"font-family:tahoma,sans-serif;font-size:large" class=3D"gmail_default=
">More information on zfs and rsync :</div><br></div><div><br></div><div><a=
href=3D"https://www.google.com/search?q=3Duse+of+rsync+command+for+zfs+vol=
umes&sxsrf=3DALiCzsZALxJWD--EizNVNAHl-u-j6BOndw%3A1668365903483&sou=
rce=3Dhp&ei=3DTz5xY6XbGrCQxc8Plbyl8A0&iflsig=3DAJiK0e8AAAAAY3FMX56s=
hwXahupzkNcfFLLhJJd0xL1U&ved=3D0ahUKEwjlvp6o66v7AhUwSPEDHRVeCd4Q4dUDCAc=
&uact=3D5&oq=3Duse+of+rsync+command+for+zfs+volumes&gs_lcp=3DCg=
dnd3Mtd2l6EAMyBQgAEKIEOgQIIxAnOgsILhCABBDHARDRAzoFCAAQgAQ6CAguENQCEIAEOggIL=
hCABBDUAjoFCC4QgAQ6CAgAEIAEEMsBOggILhCABBDLAToGCAAQFhAeOggIABAWEB4QDzoFCAAQ=
hgM6BQghEKABOgQIIRAVOggIIRAWEB4QHToHCCEQoAEQClAAWI6bAmCtnQJoAHAAeACAAbkCiAH=
kLJIBCDAuMzUuMC4xmAEAoAEB&sclient=3Dgws-wiz">https://www.google.com/sea=
rch?q=3Duse+of+rsync+command+for+zfs+volumes&sxsrf=3DALiCzsZALxJWD--Eiz=
NVNAHl-u-j6BOndw%3A1668365903483&source=3Dhp&ei=3DTz5xY6XbGrCQxc8Pl=
byl8A0&iflsig=3DAJiK0e8AAAAAY3FMX56shwXahupzkNcfFLLhJJd0xL1U&ved=3D=
0ahUKEwjlvp6o66v7AhUwSPEDHRVeCd4Q4dUDCAc&uact=3D5&oq=3Duse+of+rsync=
+command+for+zfs+volumes&gs_lcp=3DCgdnd3Mtd2l6EAMyBQgAEKIEOgQIIxAnOgsIL=
hCABBDHARDRAzoFCAAQgAQ6CAguENQCEIAEOggILhCABBDUAjoFCC4QgAQ6CAgAEIAEEMsBOggI=
LhCABBDLAToGCAAQFhAeOggIABAWEB4QDzoFCAAQhgM6BQghEKABOgQIIRAVOggIIRAWEB4QHTo=
HCCEQoAEQClAAWI6bAmCtnQJoAHAAeACAAbkCiAHkLJIBCDAuMzUuMC4xmAEAoAEB&sclie=
nt=3Dgws-wiz</a></div><div><br></div><div>use of rsync command for zfs volu=
mes</div><div><br></div><div><br></div><div><br></div><div><div style=3D"fo=
nt-family:tahoma,sans-serif;font-size:large" class=3D"gmail_default">Mehmet=
Erol Sanliturk</div><div style=3D"font-family:tahoma,sans-serif;font-size:=
large" class=3D"gmail_default"><br></div><div style=3D"font-family:tahoma,s=
ans-serif;font-size:large" class=3D"gmail_default"><br></div><div style=3D"=
font-family:tahoma,sans-serif;font-size:large" class=3D"gmail_default"></di=
v><br></div><div><br></div><div><br></div><div>=C2=A0</div></div></div>
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