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Here's my scenario: I have two servers (well many more, but two for this scenario), one is a Solaris backup server, the second is a CentOS Linux Server. Every night the CentOS server runs a cron job to rsync itself to the Solaris backup server. After this is done, it puts the date and time into a special file on the Solaris server. The Solaris server has a cron job run every minute and if it sees this file, it grabs the contents and uses that to make a snapshot.

The result is great: Every day the backup automatically runs and then creates a ZFS snapshot. Been working great for over two months. I had expected that by now I would be low on space and would need to start (manually) deleting old snapshots. But in fact, I am fine on space. My only concern is, with 60+ snapshots and more being added daily, are there any known problems with large numbers of ZFS snapshots? Is there a maximum number of ZFS snapshots a ZFS filesystem can have? Or am I OK to just keep accumulating snapshots until I am low on space?

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  • Note that after asking this I opted for a lot of snapshots using cron, and after 10 years and 42,000+ snapshots later I discovered that there's a definite space impact even though performance was still fine.
    – Josh
    Sep 8, 2021 at 21:35

2 Answers 2

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There's no problem with lots of snapshots. Having thousands of ZFS filesystems can cause boot times of more than an hour, but you're not doing that.

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  • unfortunately oracle have helpfully broken all their links so this answer is not very useful anymore
    – JamesRyan
    Jun 5, 2013 at 10:31
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    @JamesRyan Fortunately the internet archive saved a copy, so I've updated the link in my answer.
    – TRS-80
    Jul 4, 2013 at 6:16
  • What do you think of creating a snapshot on every file change? Disregard temporary files or stuff in RAMFS/TMPFS.
    – CMCDragonkai
    Jun 27, 2014 at 3:05
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I wouldn't be too concerned about this. You're talking about 1 snapshot a day here. I have heard of production environments with over 10k snapshots. But I don't have any information on how this was working for them but I didn't hear it in a bad context so I'm going to assume that it was working well.

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  • Thanks a lot! I wish I could have accepted both your answer as well as TRS-80's answer... But your was almost equally as helpful!
    – Josh
    Oct 23, 2009 at 15:28

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