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Nice. I haven't touched ZFS since it first came out on Solaris around 2008ish (we had a 48 drive "x4500", great hardware, but solaris :/ ) Are the snapshots i

• GrayShade 7y ago
  > Are the snapshots instant? Yes. But you have to remember to delete the old ones at some point.
• masklinn 7y ago
  > Are the snapshots instant? Yes, it just copies & stores the block at the top of the filesystem[0], in the same way naming a git tree will keep its content recursively alive. However all the data in the snapshot is retained as-is until the snapshot is destroyed, so as the system keeps being used and diverges from the snapshot the snapshot is slowly going to "increase in size" compared to the live FS. [0] there's also a more recent "checkpoint" concept which "saves" the entire pool by copying the uberblock.
• zenexer 7y ago
  The actual act of snapshotting doesn’t do a whole lot. I believe ZFS uses CoW for that purpose. If you modify a file after a snapshot, the file (or block) will be copied first. Normally, with CoW, the original would then be marked as free space available for writing, but if a snapshot exists, it will be preserved. (This is a general concept; I don’t know the nuances of ZFS’ approach.)
  • isostatic 7y ago
    I thought that was the case, but in more recent times they only snapshotting I've done is on AWS instances which take forever