Date: Mon, 31 May 2010 09:48:16 -0400 From: Paul Mather <paul@gromit.dlib.vt.edu> To: David Magda <dmagda@ee.ryerson.ca> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: Make ZFS auto-destroy snapshots when the out of space? Message-ID: <7B30E5C6-07F9-4B61-9F09-1615D21F6461@gromit.dlib.vt.edu> In-Reply-To: <19664824-1B23-4E5F-BC12-BB4D59A9C8AA@ee.ryerson.ca> References: <4C017419.9010909@strauser.com> <4632C12D-2B1E-4073-B2C9-E9D15C212EF1@ee.ryerson.ca> <F5E2E18E-A870-4600-9D4C-D0BE9BF68CF1@strauser.com> <19664824-1B23-4E5F-BC12-BB4D59A9C8AA@ee.ryerson.ca>
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On May 30, 2010, at 10:35 PM, David Magda wrote: > An event framework would certainly be helpful in a general sense (Linux has event(3) AFAIK), and that could certainly be useful for purging snapshots during resource constrained situations. But even if we don't have it, I doubt a fork(2) from cron(8) and a statfs(2) would be onerous on a system. :) Devd already receives several ZFS-based events (failed vdev, I/O error, checksum mismatch, etc.), so perhaps it would be useful to add another, e.g., "space" which is set to be triggered when a pool attains a certain percentage full. This could default to 100%, but be capable of being set lower by an associated kernel sysctl. You could then have any auto-pruning/snapshot management script triggered from devd. (You'd probably also have to figure out some kind of throttling mechanism for this devd event, too.) Cheers, Paul.
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