Zrepl – ZFS replication

https://zrepl.github.io/

by lnyan • 3 years ago

252 57 3 years ago

zrepl.github.io

tamimio3• 3 years ago

Off topic: This is a great example why github stars don’t mean anything, such a great tool like this is ~600 while other repos that are basically toys compared to this have ~12k stars!

mekster• 3 years ago

Can you be more specific? What makes this so much better than others?

r1ch3• 3 years ago

For me one of the key features is the integrated TLS server, so my backups can be transferred over the internet at decent speeds. Tools based on SSH all suffer from the SSH window limit and will never reach high speeds over the internet.

thejosh• 3 years ago

Niche tools usually have low star count.

alias_neo• 3 years ago

They do though, don't they? They indicate interest or popularity. Their purpose is not to demonstrate the quality or usefulness of a thing, but how popular it is.

When I choose libraries or tools for work, let's say I need a Go library for something; I use the star count and the commit activity together to determine whether a project is popular enough (vs others) to use over the others.

jraph• 3 years ago

Maybe users using such a tool are less likely to use stars.

I don't look at stars or fork count. To see if I should use a tool or a library, I'll be seeking technical blog posts and reviews.

I don't like how software development is centering around GitHub, and how it is handled like a social network.

Wha's more, you can't know why someone added a star. Maybe they found something random cool in the project, or found it looks cool but haven't really tried, and most importantly, you don't know if they added a star after some time, building some solid experience with the library or the tool.

This metric doesn't even exist for projects not developed on GitHub and many worthy ones are indeed elsewhere. And I suppose many of us don't use stars on GitHub, so you are only ever going to measure "popularity" aka "I liked something here" of only a part of the population that is willing to star things.

It's also probably a self-sustaining process: people are not going to give stars to alternative projects they haven't tried... because the first one had more stars in the first place! This feature is probably quite misleading in the end.

In a previous job, the number of forks and stars, as well as recent commits played an important choice when choosing a library. I hated this. It lead to some bad choices and technical dept.

In short, when you are considering stars, you are looking at a self-sustained process, sustained only by people who participate in it, and that is GitHub-specific (excluding interesting projects that happen to not be hosted there). This thing probably pushes the actual popularity of some projects for reasons that are likely very random, at times. GitHub is not making us a favor with this feature.

Commit history or activity in the bug tracker is somewhat important (though sometimes a project doesn't receive so many commits because it is stable enough). The social media gamification things on GitHub like counts and badges should just be ignored, don't fall for it and its addictive aspect.

tamimio3• 3 years ago

Couldn’t agree more!

sgarland2• 3 years ago

This has 695 stars, pyznap (what I’ve been using) has 187 stars, and sanoid has 2.6K stars. They all seem roughly at parity in terms of features, with one notable exception: Prometheus endpoint (and a preconfigured Grafana dashboard). I monitor mine with a fairly hacky script that parses logs and then sends a push to my phone. It’s very brittle, and I’ve found edge cases where it fails, but reports success.

I’ll probably give zrepl a try based solely on that.

tamimio3• 3 years ago

I meant repos in general not specific to zfs/backup tools, without mentioning some of these repos as it might end up in flame wars.

Femolo• 3 years ago

I do my zfs snapshots with a few lines of script with what zfs offers out of the box.

I like this script but never heard from it and probably will not look at it for a while.

jeffalyanak• 3 years ago

ZFS already includes all the functionality and commands you would need for replication—you _could_ do it yourself with snapshot, bookmark, send, and receive—but Zrepl is such a great way to define/manage it that it's always on my list of must-have ZFS tools.

crest• 3 years ago

There are two kinds of backups: automatic and forgotten.

philjohn• 3 years ago

You forgot: automatic, but never verified if they can be restored.

sofixa• 3 years ago

Or two other types - tested or non-existent.

3np• 3 years ago

I opened a couple of issues and did some minor contributions in the past and at every point problame has been approachable and a pleasure to interact with.

From a user perspective, I'm still feeling a lack of UX in restoration/clone-management from the snapshots synced by zrepl - things can easily get messy if you don't know exactly what you're doing and keep track of things properly. That might be out of scope for zrepl itself, though.

Some more proactive/pre-emptive pruning would also be great - falling behind on syncing can be downright painful if you don't pay attention... Which is just to say, don't skip setting up some basic monitoring with alerts for production loads (:

Either way, all things considered zrepl is the nicest zfs replication option I found so far.

tomatocracy• 3 years ago

If you haven't already seen it, for restoring files/browsing different snapshots etc, httm is great: https://github.com/kimono-koans/httm

baggiponte• 3 years ago

I did not understand what is ZFS - could anyone be so kind to explain?

voxadam• 3 years ago

ZFS is an advanced file system with integrated multi-device volume management. It was originally designed and implemented by Sun Microsystems for their Unix operating system Solaris. The copyright for the original codebase is now owned by Oracle and has since been closed up and made proprietary software. Prior to Oracle's acquisition of Sun, ZFS was made open source under the CDDL as part of OpenSolaris, that code was forked and it gave rise to OpenZFS which is used by many Linux and BSD users.

https://en.wikipedia.org/wiki/ZFS

https://openzfs.org

chasil• 3 years ago

Here are a couple of introductions.

https://news.ycombinator.com/item?id=25157491

https://www.linuxjournal.com/content/zfs-linux

ilyt3• 3 years ago

It's like someone glued together LVM and RAID but on file level instead of block level.

So you can make some fancy things like (relatively) cost-free snapshots, and some extra data safety with per-file checksumming. It also uses WAL (similarly to databases) which allows (similiar to databases) replication to remote system.

edmundsauto• 3 years ago

Got it, that makes sense! Not OP but a followup - what does "replication" mean in this context? Is it mirroring your ZFS volumes in another device?

AndroTux2• 3 years ago

I started using ZFS a few years ago. Before that I didn't know that I could develop such a strong feeling towards a file system. But here we are. In my mind, it really revolutionized the meaning of file system. It feels like much more than that, especially when compared to something like NTFS or ext4.

HankB992• 3 years ago

Disclaimer: I'm a huge fan of ZFS.

ZFS is much more than just a filesystem and related tools. It also supports backup/restore and disk partitioning and partitioning of data via filesystems (not AFAIK available with EXT4.) And probably other things I either don;t know about or have forgotten to mention.

cryptonector• 3 years ago

ZFS is life-altering.

lprd• 3 years ago

Similar story here (truenas was a gateway drug). There are a few up and coming filesystems that I have my eye on. But by and large, ZFS has remained my favorite.

imiric4• 3 years ago

I've been curious about ZFS ever since it became stable in Linux, but haven't made the jump yet because a) I have an irrational fear of data loss, and ext4 has never failed me, and b) I have an aversion towards complexity, and ZFS is much more complex than ext4. Features like snapshots and checksumming can be accomplished with userspace tools, though in arguably less elegant ways, so I didn't have a strong need for it either.

That said, it's great reading its success stories and praises, and my next system will use ZFS. :)

tombert3• 3 years ago

Potential complexity is higher with ZFS, but in regards to RAID and the like, I honestly find the zpool tools to be much easier to work with than their mdadm equivalents.

I have a "ghetto NAS" of 24 drives plugged into my server via USB, and getting a raidz3 set up on there was one command:

`zpool create tank raidz3 drive1 drive2 drive3 ....`

Doing scrubs and replacing disks are pretty easy, just using `scrub` and `replace` commands with zpool.

I haven't really felt the need to leave ZFS, at least not in regards to RAIDs; on root I still use ext4, though I might change to btrfs on my next install.

giantrobot2• 3 years ago

I have an irrational fear of data loss, and ext4 has never failed me

You're a lot more likely to lose/corrupt data with ext4 than ZFS. Ext4 will happily corrupt data silently. The core conceit of ZFS is it doesn't trust the underlying hardware. ZFS even allows duplicated data on a single disk. You lose capacity but gain robustness.

jjav2• 3 years ago

I have an irrational fear of data loss

If you have an irrational fear of data loss (it's really quite rational), zfs is the only place you should be comfortable.

I've been on zfs since its earliest days (~2004-ish, inside Sun at the time) and never lost a single byte ever since. Computers and hard drives have died but zfs just rocks on.

ZeWaren2• 3 years ago

I'm using zrepl to sync ZFS filesystems incrementally between servers.

I like the ability to incrementally send only the changes of an encrypted filesystem to a target server that never had the encryption key at anytime.

I'm using this to share backup space with my friends. We both push/pull our encrypted snapshot diffs every hour. I don't have my friends' keys so I can't read their data, and they can't read mine. In case of emergency, I can go to their place with my key, and recover my data from their systems.

HankB992• 3 years ago

Have you used sanoid/syncoid? I started my ZFS journey with a custom script and then switched to syncoid/sanoid (and some much simplified scripts) for my backup needs. One of my use cases is for Raspberry Pis which seem to have a habit of becoming unbootable. These are Pi 4Bs running from SATA/USB SSD or CM4s using NVME SSDs. I have scripts that use

* dd to copy the boot sector (to a ZFS filesystem) * rsync to copy the boot (FAT32) and root (EXT4) partitions (also to a ZFS filesystem) * syncoid to copy the ZFS filesystem to another host.

This process runs daily. When a system craps, it's pretty straightforward to restore the boot sector and boot and root partitions and finally the ZFS pool.

I'm curious zrepl does that might be useful for me.

ZeWaren2• 3 years ago

I don't need to backup my boot sectors or root partitions since all my systems are provisioned. I can always re-create them with scripts, should any of them fail.

I'm only replicating the data filesystems.

From what I see, sanoid looks quite similar to zrepl. Both tools are probably able to achieve similar results.

I do feel that zrepl has more features so far, though. But hey, if your setup is working and your data is secure, that's the most important.

amar0c• 3 years ago

I do not see benefit using this over Sanoid/Syncoid. This smells 'complicated' comparing two

ewwhite• 3 years ago

Syncoid is the way. Zrepl was more fraught in my use cases and significantly more complicated.

mdtancsa• 3 years ago

really excellent software I have been using for a long time to manage snapshots!

harvie• 3 years ago

I have rather nice experience with ZnapZend https://www.znapzend.org/

Only issue i've found is the fact there is no official Debian repository and i always do forget to recompile it after upgrading Debian :-D

I really like the configuration system integrated in ZFS set/get...

rsync• 3 years ago

zrepl works perfectly with an rsync.net account as a target:

https://news.ycombinator.com/item?id=32014969

Here's a nice summary someone wrote:

https://blog.lenny.ninja/zrepl-on-rsync-net.html

contingencies• 3 years ago

How timely... literally spent the last hour attempting to recover data from 7 year old ZFS volumes. The conclusion was I think they must have been LVM'd or something before ZFS pool creation because cfdisk and hexdump -C show ZFS pool evidence but zpool-import won't scan them for love nor money. Only other option is an older-than-thou ZFS kernel module version with breaking changes. Sigh. Calling it a fail. No anticipated data of any weight and meaning, IIRC, but one likes to be thorough.

Also had a dead 6TB hard disk this morning: WD60EZAZ. Tried replacing the PCB as I had a few functional ones (ex RAID array), happened to have the right security bit, but no dice. You can hear it try to take-off repeatedly but it never achieves altitude. It's been awhile!

dshdsh• 3 years ago

Hm... According to commit activity and high number of issues, looks like this project is almost dead. Anyway I tried to use it once and I got an impression it's too complicated and unreliable. I don't remember any details.

Zrepl – ZFS replication

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