From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: SSD - TRIM command Date: Mon, 21 Feb 2011 15:25:03 -0300 Message-ID: References: <4D517F4F.4060003@gmail.com> <4D5245DF.4020401@hardwarefreak.com> <4D62ACFE.4020401@cfl.rr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <4D62ACFE.4020401@cfl.rr.com> Sender: linux-raid-owner@vger.kernel.org To: Phillip Susi Cc: David Brown , linux-raid@vger.kernel.org List-Id: linux-raid.ids TRIM is a new feature for many hard disk/ssd it=B4s more to get a bigger life o disk, allow a dynamic badblock reallocation (filesystem must tell where is empty) 2011/2/21 Phillip Susi : > On 2/9/2011 10:49 AM, David Brown wrote: >> I've been reading a little more about this. =A0It seems that the day= s of >> TRIM may well be numbered - the latest generation of high-end SSDs h= ave >> more powerful garbage collection algorithms, together with more spar= e >> blocks, making TRIM pretty much redundant. =A0This is, of course, th= e most >> convenient solution for everyone (as long as it doesn't cost too muc= h!). >> >> The point of the TRIM command is to tell the SSD that a particular b= lock >> is no longer being used, so that the SSD can erase it in the backgro= und >> - that way when you want to write more data, there are more free blo= cks >> ready and waiting. =A0But if you've got plenty of spare blocks, it's= easy >> to have them erased in advance and you don't need TRIM. > > It is not just about having free blocks ready and waiting. =A0When do= ing > wear leveling, you might find an erase block that has not been writte= n > to in a long time, so you want to move that data to a more worn block= , > and use the less worn block for more frequently written to sectors. =A0= If > you know that sectors are unused because they have been TRIMed, then = you > don't have to waste time and wear copying the junk there to the new > flash block. > > TRIM is also quite useful for thin provisioned storage, which seems t= o > be getting popular. > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > --=20 Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html