Date: Thu, 30 Sep 2021 20:06:28 -0700 From: David Christensen <dpchrist@holgerdanske.com> To: freebsd-questions@freebsd.org Subject: Re: zfs q regarding backup strategy Message-ID: <ba54a415-da45-e662-73fe-65702c4131e2@holgerdanske.com> In-Reply-To: <YVZM1HnPuwIUQpah@ceres.zyxst.net> References: <YVZM1HnPuwIUQpah@ceres.zyxst.net>
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On 9/30/21 16:48, tech-lists wrote: > Hi, > > This is a bit chicken-and-egg for me, in that I might be formulating the > wrong question, and so getting wrong answers, so I apologise in advance > if I'm being dense. > > Basically the end result I want is to be in a position at a backup site > with full backups that can be restored to the live site if needed, or > even to get just one required file from that backup, given the filename > and modification time. The backup site has very much more diskspace than > the live site. > > I know how to make the full backup and to send it. What I'm looking for > is incremental (or would it be differential) zfs backups (snapshots). So > let's say an incremental/differential backup to the remote site happens > every 6hrs. > > If 10 incremential backups happen after the full one, and on the > live service someone loses a few files, later adding another few, maybe > a couple of those have the same name as before just with a different > modification time, all the while this is happening 24hrs pass. > > How are the accumulated differential/incremental snaps incorporated into > the main backup? Would I need to run something else on the backup > server to integrate the snaps with the full backup? Or would all the > snaps need to be kept? > How would one tell if the required files in this example are in one snap > and not in the others? > > If the policy was to keep everything in backup regardless of whether it > was deleted or not from the live service (so the backup is like a > write-only representation) I guess the approach would be different to > say if the backup just had to be the latest representation of the data > on the live server. But if it's "keep everything" then what happens > if the live server makes foo.txt then deletes it then makes foo.txt 10 > days later in the same place? All the while these > (incremental/differential) snaps have been arriving every 6 hrs. > > Additionally the live site is the old zfs on releng/12.2-p10 and the > backup site is with the OpenZFS on stable/13 which might be an issue > if they handle things significantly differently. > > thanks advance for any suggestions or any scripts/tools you can > recommend. I have a SOHO environment with a FreeBSD 12.2-RELEASE machine providing Samba and CVS services. Michael Warren Lucas is my go-to author for FreeBSD and ZFS: https://mwl.io/nonfiction/os https://mwl.io/archives/2128 https://mwl.io/archives/2140 I use zfs-auto-snapshot for snapshot creation/ management, and homebrew commands/ scripts for replication. The homebrew stuff is problematic. I need to evaluate something like zfs-replicate (available as a FreeBSD package of the same name): https://pypi.org/project/zfs-replicate/ David
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