Date: Fri, 22 Feb 2019 22:40:06 +0200 From: Stefan Parvu <sparvu@kronometrix.org> To: freebsd-arm@freebsd.org Subject: Re: RBPI3B+ FreeBSD 12 ZFS Message-ID: <83C65D08-F8ED-4EB1-990C-E043D45E654D@kronometrix.org> In-Reply-To: <20190222185613.GA50742@server.rulingia.com> 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> <20190222185613.GA50742@server.rulingia.com>
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Thanks all for comments. I need to dedicate time to play around with ZFS and RBPI3. Cheers Stefan Parvu sparvu@kronometrix.org > On 22 Feb 2019, at 20.56, Peter Jeremy <peter@rulingia.com> wrote: > > 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
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