Date: Fri, 14 Jan 2022 16:32:10 +0100 From: Christian Weisgerber <naddy@mips.inka.de> To: freebsd-questions@freebsd.org Subject: Re: zero filling a storage device (was: dd and mbr) Message-ID: <YeGXejPepsd4aKiE@lorvorc.mips.inka.de> In-Reply-To: <YeDryNdYe1S20wd2@neutralgood.org> References: <77680665-7ddb-23c5-e866-05d112339b60@holgerdanske.com> <20220114023002.GP61872@eureka.lemis.com> <YeDryNdYe1S20wd2@neutralgood.org>
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"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.) -- Christian "naddy" Weisgerber naddy@mips.inka.de
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