Date: Sat, 10 Feb 2018 12:21:50 -0700 From: Alan Somers <asomers@freebsd.org> To: Willem Jan Withagen <wjw@digiware.nl> Cc: freebsd current <freebsd-current@freebsd.org> Subject: Re: posix_fallocate on ZFS Message-ID: <CAOtMX2jbPg3aueacbwJX2REEMoxaFkvdzuY47KahEYNj0SgQ2w@mail.gmail.com> In-Reply-To: <985b6d77-9f27-f6f4-ea0e-165951d91048@digiware.nl> References: <1e2f43fd-85da-6629-62d1-6e96790278e5@digiware.nl> <CAOtMX2jZr_kvJgOZWeiB-AZ3-7-uUu%2BUQ3P0nKhGZ0eNRzwMOQ@mail.gmail.com> <985b6d77-9f27-f6f4-ea0e-165951d91048@digiware.nl>
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On Sat, Feb 10, 2018 at 11:50 AM, Willem Jan Withagen <wjw@digiware.nl> wrote: > On 10/02/2018 19:24, Alan Somers wrote: > >> On Sat, Feb 10, 2018 at 10:28 AM, Willem Jan Withagen <wjw@digiware.nl >> <mailto:wjw@digiware.nl>> wrote: >> >> Hi, >> >> This has been disabled on ZFS since last November. >> And I do understand the rationale on this. >> >> BUT >> >> I've now upgraded some of my HEAD Ceph test systems and they now >> fail, since Ceph uses posix_fallocate() to allocate space for the >> FileStore-journal. >> >> Is there any expectation that this is going to fixed in any near >> future? >> >> --WjW >> >> >> No. It's fundamentally impossible to support posix_fallocate on a COW >> filesystem like ZFS. Ceph should be taught to ignore an EINVAL result, >> since the system call is merely advisory. >> > > Yup, that was what I'm going to do. > But then I would like to know how to annotate it. > > And I guess that I'd get reactions submitting code to fix this, since the > journal could run out of space. > So I'd beter know what is going on. > > I seem to remember that on a pool level is is possible to reserve space > whilest creating a filesystem? And then it could/should be fixed when > building the disk-infra for an OSD. > Yes, you can easily reserve space for an entire filesystem. Just do for example "zfs create -o reservation=64GB mypool/myfs" .
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