Date: Fri, 14 Jan 2022 17:14:18 +0000 From: Arthur Chance <freebsd@qeng-ho.org> To: Christian Weisgerber <naddy@mips.inka.de>, freebsd-questions@freebsd.org Subject: Re: zero filling a storage device (was: dd and mbr) Message-ID: <523b6b6d-b17c-e632-a36a-a8c26ad61798@qeng-ho.org> In-Reply-To: <YeGXejPepsd4aKiE@lorvorc.mips.inka.de> References: <77680665-7ddb-23c5-e866-05d112339b60@holgerdanske.com> <20220114023002.GP61872@eureka.lemis.com> <YeDryNdYe1S20wd2@neutralgood.org> <YeGXejPepsd4aKiE@lorvorc.mips.inka.de>
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On 14/01/2022 15:32, Christian Weisgerber wrote: > "Kevin P. Neal": > >> Are we certain that an SSD won't at least track that there is nothing >> written to a logical block and therefore it must be all zeros? I'm not >> 100% that an SSD will always keep a logical block assigned to a physical >> block. And I'm not 100% certain that an SSD won't notice that all zeros >> are being written to a block and just optimize out the write. > > It's tempting to speculate that an SSD could treat an all-zeros > block write effectively like a TRIM. > > I'll note that there are SSDs that compress the data written to > them. (Compression in storage devices isn't new. Terry Welch's > 1984 paper, where he presented the LZW compression algorithm, already > talks about this.) > May I suggest "man trim"? (From 12.1 onwards.) -- Nothing teaches one not to try to stamp out burning thermite quite like real-life experience. — James Davis Nicoll
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