3 ms·

> I can see a good argument for more fine grained snapshots (e.g. every few minutes) but I think I'd limit that to directories (and thus FSes) known to have fre

> I can see a good argument for more fine grained snapshots (e.g. every few minutes) but I think I'd limit that to directories (and thus FSes) known to have frequent updates. Fun fact, the ZFS send-receive functionality was born with snapshots being created every few minutes in mind: > ZFS send and receive wasn’t considered until late in the development cycle. The idea came to me in 2005. ZFS was nearing integration, and I was spending a few months working in Sun’s new office in Beijing, China. The network link between Beijing and Menlo Park was low-bandwidth and high-latency, and our NFS-based source code manager was painful to use. I needed a way to quickly ship incremental changes to a workspace across the Pacific. A POSIX-based utility (like rsync) would at best have to traverse all the files and directories to find the few that were modified since a specific date, and at worst it would compare the files on each side, incurring many high-latency round trips. I realized that the block pointers in ZFS already have all the information we need: the birth time allows us to quickly and precisely find the blocks that are changed since a given snapshot. It was easiest to implement ZFS send at the DMU layer, just below the ZPL. This allows the semantically-important changes to be transferred exactly, without any special code to handle features like NFSv4 style ACLs, case-insensitivity, and extended attributes. Storage-specific settings, like compression and RAID type, can be different on the sending and receiving sides. What began as a workaround for a crappy network link has become one of the pillars of ZFS, and the foundation of several remote replication products, including the one at Delphix. * https://www.delphix.com/blog/delphix-engineering/zfs-10-year-anniversary https://www.delphix.com/blog/delphix-engineering/zfs-10-year...

ptomato 5y ago
It remains a _delightfully_ straightforward way to do backups; I do incremental zfs send with hourly snapshots to my local NAS and also to an rsync.net ZFS account (https://www.rsync.net/products/zfsintro.html); https://www.rsync.net/products/zfsintro.html); it's incredibly resource un-intensive relative to your traditional scan-everything backup methods and I can trivially mount a past snapshot for browsing or spot restore or just do zfs send on the whole thing for catastrophic recovery.
- throw0101a 5y ago
  As an added bonus, with (Open)ZFS encryption, you can send the 'raw' encrypted zfs send stream (over an encrypted SSH connection) to a destination where the file system is encrypted and where the zfs receive command does not have to decrypt it to save things. That is, the remote destination does not need to have the key/passphrase to the file system to have an (encrypted) copy of the data. If your production server goes down, you can restore the encrypted file system without the encryption key, and only when you try to mount the restored ZFS file system will you be prompted for the key/passphrase. > This means that you can use ZFS replication to back up your data to an untrusted location, without concerns about your private data being read. With raw send, your data is replicated without ever being decrypted—and without the backup target ever being able to decrypt it at all. This means you can replicate your offsite backups to a friend's house or at a commercial service like rsync.net or zfs.rent without compromising your privacy, even if the service (or friend) is itself compromised. * https://arstechnica.com/gadgets/2021/06/a-quick-start-guide-to-openzfs-native-encryption/ https://arstechnica.com/gadgets/2021/06/a-quick-start-guide-...
  - cyberpunk 5y ago
    Do you happen to know if rsync.net supports this?
    - throw0101a 5y ago
      They support zfs send-recv and snapshots: * https://www.rsync.net/products/zfsintro.html https://www.rsync.net/products/zfsintro.html * https://www.rsync.net/resources/howto/snapshots.html https://www.rsync.net/resources/howto/snapshots.html Whether their ZFS implementation supports OpenZFS encryption is something you'll have to e-mail them about. They have an HN account: * https://news.ycombinator.com/user?id=rsync https://news.ycombinator.com/user?id=rsync Edit: Yes, it seems that they do: * https://news.ycombinator.com/item?id=26506263 https://news.ycombinator.com/item?id=26506263
    - rsync 5y ago
      "Do you happen to know if rsync.net supports this?" Yes, we do. If you get a zpool from us (which is a bit different than a "normal" rsync.net account) it is running the latest stable ZoL codebase and, thus, supports encryption and "raw send", etc. However ... As elegant and performant as 'zfs send' is, the benefits are realized in large datasets where efficiency and performance really matters. If you're just sending 200 or 400 or 800 GB of data to an untrusted destination (like rsync.net) you should probably just use borg[1][2]. [1] https://borgbackup.readthedocs.io/en/stable/ https://borgbackup.readthedocs.io/en/stable/ [2] https://www.stavros.io/posts/holy-grail-backups/ https://www.stavros.io/posts/holy-grail-backups/
jiggawatts 5y ago
> rsync ... incurring many high-latency round trips. If I remember correctly, the rsync protocol is actually very nearly optimal in terms of minimising round trips.
- ptomato 5y ago
  If you have to actually compare the files on both ends, however, that's still many more round trips than necessary for zfs send, which is just sending all blocks with a birth time after the previous snapshot

ptomato 5y ago

It remains a _delightfully_ straightforward way to do backups; I do incremental zfs send with hourly snapshots to my local NAS and also to an rsync.net ZFS account (https://www.rsync.net/products/zfsintro.html); https://www.rsync.net/products/zfsintro.html); it's incredibly resource un-intensive relative to your traditional scan-everything backup methods and I can trivially mount a past snapshot for browsing or spot restore or just do zfs send on the whole thing for catastrophic recovery.

throw0101a 5y ago
As an added bonus, with (Open)ZFS encryption, you can send the 'raw' encrypted zfs send stream (over an encrypted SSH connection) to a destination where the file system is encrypted and where the zfs receive command does not have to decrypt it to save things. That is, the remote destination does not need to have the key/passphrase to the file system to have an (encrypted) copy of the data. If your production server goes down, you can restore the encrypted file system without the encryption key, and only when you try to mount the restored ZFS file system will you be prompted for the key/passphrase. > This means that you can use ZFS replication to back up your data to an untrusted location, without concerns about your private data being read. With raw send, your data is replicated without ever being decrypted—and without the backup target ever being able to decrypt it at all. This means you can replicate your offsite backups to a friend's house or at a commercial service like rsync.net or zfs.rent without compromising your privacy, even if the service (or friend) is itself compromised. * https://arstechnica.com/gadgets/2021/06/a-quick-start-guide-to-openzfs-native-encryption/ https://arstechnica.com/gadgets/2021/06/a-quick-start-guide-...
- cyberpunk 5y ago
  Do you happen to know if rsync.net supports this?
  - throw0101a 5y ago
    They support zfs send-recv and snapshots: * https://www.rsync.net/products/zfsintro.html https://www.rsync.net/products/zfsintro.html * https://www.rsync.net/resources/howto/snapshots.html https://www.rsync.net/resources/howto/snapshots.html Whether their ZFS implementation supports OpenZFS encryption is something you'll have to e-mail them about. They have an HN account: * https://news.ycombinator.com/user?id=rsync https://news.ycombinator.com/user?id=rsync Edit: Yes, it seems that they do: * https://news.ycombinator.com/item?id=26506263 https://news.ycombinator.com/item?id=26506263
  - rsync 5y ago
    "Do you happen to know if rsync.net supports this?" Yes, we do. If you get a zpool from us (which is a bit different than a "normal" rsync.net account) it is running the latest stable ZoL codebase and, thus, supports encryption and "raw send", etc. However ... As elegant and performant as 'zfs send' is, the benefits are realized in large datasets where efficiency and performance really matters. If you're just sending 200 or 400 or 800 GB of data to an untrusted destination (like rsync.net) you should probably just use borg[1][2]. [1] https://borgbackup.readthedocs.io/en/stable/ https://borgbackup.readthedocs.io/en/stable/ [2] https://www.stavros.io/posts/holy-grail-backups/ https://www.stavros.io/posts/holy-grail-backups/

jiggawatts 5y ago

> rsync ... incurring many high-latency round trips. If I remember correctly, the rsync protocol is actually very nearly optimal in terms of minimising round trips.

ptomato 5y ago
If you have to actually compare the files on both ends, however, that's still many more round trips than necessary for zfs send, which is just sending all blocks with a birth time after the previous snapshot