Date: Sat, 23 Feb 2019 05:56:13 +1100 From: Peter Jeremy <peter@rulingia.com> To: Karl Denninger <karl@denninger.net> Cc: freebsd-arm@freebsd.org Subject: Re: RBPI3B+ FreeBSD 12 ZFS Message-ID: <20190222185613.GA50742@server.rulingia.com> In-Reply-To: <00523016-b7eb-8a61-8740-7463d793f969@denninger.net> References: <E387BB48-540D-4F5C-BD4D-2BF410108219@kronometrix.org> <a0239ad1-5b98-1149-1d14-966ed8670e79@denninger.net> <5D976A97-9800-4A9F-A155-F3BD998AFB4C@kronometrix.org> <facfaeae8cef0351b91194ed0b7e30345139e668.camel@freebsd.org> <B76D999D-F908-43AB-A70B-EA102EFCF02B@kronometrix.org> <CAFnjQbvMymVRmimSi1%2B1sY9%2BJYQ-dkzZ6sKOw_XFviujy3wF9w@mail.gmail.com> <00523016-b7eb-8a61-8740-7463d793f969@denninger.net>
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[-- Attachment #1 --] On 2019-Feb-22 11:47:37 -0600, Karl Denninger <karl@denninger.net> wrote: >Uh uh. Yes, a scrub (or just checksum check on the read) will catch the >"aw crap!" situation where write amplification and read/rewrite hoses >you during a power failure but there's nothing zfs can do to fix it >since there's no second copy available. That's not completely true. By default ZFS stores 2 copies of most metadata and can be configured to store up to 3 copies (on top of pool redundancy) of all data (check the "copies" and "redundant_metadata" properties of the filesystem). Obviously, if all the copies are on one device, it won't help if the device bricks itself or all the copies wind up on the corrupt sectors but it can help recovering from a glitch that took out a page or two. (It would also be possible to setup a ZFS mirror between a SDcard and a USB flash stick). -- Peter Jeremy [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE7rKYbDBnHnTmXCJ+FqWXoOSiCzQFAlxwRc1fFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEVF QjI5ODZDMzA2NzFFNzRFNjVDMjI3RTE2QTU5N0EwRTRBMjBCMzQACgkQFqWXoOSi CzTAzw//bjqX2ifsfTn3Bv4k+8uuqKe8ywqs7rDaev6NIMNgLV+0dALPfSnhXEKJ jYOXYkoVNnIw+x7UcaxZxzIWLip5acZDqSssry9B+ifj02lxe5n08Ex5CbIzG0aF 1DmQV3ShmOanb50IF7cZ7Gr3cQYxfQ4P2oRfpOW24UbkN+mJXl544wWjGMfi/Yn6 3DckQMiiDzIzZkM2aHhqykO2Wr7KrEU0UAIbAGIoNJl3/rtRyCoVFsjT7QNtiEOW Q4YW+NrrpvRqVdlEAsNN8Snmm9bdAuPH83Csm3VipVaug+EmvP+RFMEbYY46WtTR ubRqn5F6DL0MOC1yGoewc6F0M2N571+dzLD0eyX11uGD85CkAl/CEUXnwfZDSFjc VqAnV8ilPzxihPUvaxMdYd7ZoAIksPkavcnNGYejaS4csfEW52BWzha6Iy4/zhSH 2d5F30255WYGB3cKV9e7oe3tLiOAAfAuszmJlRQT+pKpURMNq9VS/BhNkPre4msE zJt80C1MlupcY2Jw6rmudeWaRsZB2OjXFPW0g/2Dc4250P5vKldsCAnLFWiq6O02 rdm6/SZBQ5PkPSVfXFsjJClWWfWlzxMfC9CaFkmQoZem2UvFZcqqliQgPdEf3mu8 RCMCiZwaifwn/4mtxr7KOlZ9HGygVkR4arxepvQtNfABXvKecAM= =CIEL -----END PGP SIGNATURE-----home | help
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