Re: Odd behaviour of two identical ZFS servers mirroring via rsync
- In reply to: Bob Friesenhahn : "Re: Odd behaviour of two identical ZFS servers mirroring via rsync"
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Date: Sun, 13 Nov 2022 19:03:15 UTC
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 helps > > 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.txt > > More information on zfs and rsync : https://www.google.com/search?q=use+of+rsync+command+for+zfs+volumes&sxsrf=ALiCzsZALxJWD--EizNVNAHl-u-j6BOndw%3A1668365903483&source=hp&ei=Tz5xY6XbGrCQxc8Plbyl8A0&iflsig=AJiK0e8AAAAAY3FMX56shwXahupzkNcfFLLhJJd0xL1U&ved=0ahUKEwjlvp6o66v7AhUwSPEDHRVeCd4Q4dUDCAc&uact=5&oq=use+of+rsync+command+for+zfs+volumes&gs_lcp=Cgdnd3Mtd2l6EAMyBQgAEKIEOgQIIxAnOgsILhCABBDHARDRAzoFCAAQgAQ6CAguENQCEIAEOggILhCABBDUAjoFCC4QgAQ6CAgAEIAEEMsBOggILhCABBDLAToGCAAQFhAeOggIABAWEB4QDzoFCAAQhgM6BQghEKABOgQIIRAVOggIIRAWEB4QHToHCCEQoAEQClAAWI6bAmCtnQJoAHAAeACAAbkCiAHkLJIBCDAuMzUuMC4xmAEAoAEB&sclient=gws-wiz use of rsync command for zfs volumes Mehmet Erol Sanliturk