From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: SSD Optimizations Date: Thu, 11 Mar 2010 11:22:44 -0500 Message-ID: References: <4B97F7CE.4030405@bobich.net> <4B9829B1.1020706@bobich.net> <20100311073853.GA26129@attic.humilis.net> <201003111159.58081.hka@qbs.com.pl> <7832455d62f27d8fb89a7c40ac3cd386@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: To: Gordan Bobic Return-path: In-Reply-To: <7832455d62f27d8fb89a7c40ac3cd386@localhost> (Gordan Bobic's message of "Thu, 11 Mar 2010 12:09:29 +0000") List-ID: >>>>> "Gordan" == Gordan Bobic writes: Gordan> I fully agree that it's important for wear leveling on flash Gordan> media, but from the security point of view, I think TRIM would Gordan> be a useful feature on all storage media. If the erased blocks Gordan> were trimmed it would provide a potentially useful feature of Gordan> securely erasing the sectors that are no longer used. It would Gordan> be useful and much more transparent than the secure erase Gordan> features that only operate on the entire disk. Just MHO. Except there are no guarantees that TRIM does anything, even if the drive claims to support it. There are a couple of IDENTIFY DEVICE knobs that indicate whether the drive deterministically returns data after a TRIM. And whether the resulting data is zeroes. We query these values and report them to the filesystem. However, testing revealed several devices that reported the right thing but which did in fact return the old data afterwards. -- Martin K. Petersen Oracle Linux Engineering