We want to keep quite regular (5 minute) snapshots of certain zvols. But are also concerned about how long we should be keeping them and how much memory they use. Is there a way to check how much memory the snapshots are using? We're using FreeNAS if that matters.
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Snapshots do not consume RAM but rather disk space which depends on the rate of change of the original filesystem. – Thomas Oct 09 '19 at 11:04
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@Thomas They consume memory as well I believe. An index is kept in memory and updated whenever there is file changes. – Levi H Oct 09 '19 at 11:15
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I guess you refer to deduplication which is RAM consuming and can be tricky, which is why ZFS 0.8 introduced special class vdevs. – Thomas Oct 09 '19 at 11:22
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@Thomas I'm just referring to normal snapshots, dedup is off (except the snapshot deduping of course). I just looked it up again, and yes, snapshot metadata is stored in memory so that it can be updated when something changes on the relevant file system. What I'm looking for is actual statistics of how much they're taking. – Levi H Oct 09 '19 at 11:43
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Can you share the source where you read that? – Thomas Oct 09 '19 at 11:48