Date: Mon, 21 Mar 2016 20:38:13 -0600 From: Warner Losh <imp@bsdimp.com> To: Jim Thompson <jim@netgate.com> Cc: Ian Lepore <ian@freebsd.org>, freebsd-arm@freebsd.org Subject: Re: Effect of partitioning on wear-leveling Message-ID: <CANCZdfrCWXAswe02Qd3tTiDL8O_4TGEWbhFqgft4Q9aKj7ixvg@mail.gmail.com> In-Reply-To: <1973487B-0AA7-468D-A9CC-319FBE2122F0@netgate.com> References: <20160321175952.GA83908@www.zefox.net> <1458586884.68920.96.camel@freebsd.org> <20160321221153.GB83908@www.zefox.net> <1458600070.68920.107.camel@freebsd.org> <1973487B-0AA7-468D-A9CC-319FBE2122F0@netgate.com>
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On Mar 21, 2016 8:15 PM, "Jim Thompson" <jim@netgate.com> wrote: > > > > On Mar 21, 2016, at 4:41 PM, Ian Lepore <ian@freebsd.org> wrote: > > > > Also, it's been my experience that it's impossible to "wear out" an > > sdcard. I once ran a program that just wrote random data continuously > > at full speed to a 512MB card for several months nonstop. No noticible > > effect on the card. I actually still use that card today (in one of > > our older products whose filesystem image only needs about 40MB). > > Now try random power fails while writing. It won't last through 1000 of them. (eMMC is way better One thing that people forget is that the underlying blocks that are written are completely independent of what lba is used to write it. So the notion that you have blocks normally part of /var or /tmp no longer makes sense. Between writing blocks in different order and garbage collection, modern SD cards do a good job of wear averaging. How much you've written to the drive in total drives wear out these days. Warner
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