From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Mathias_Bur=C3=A9n?= Subject: Re: SSD - TRIM command Date: Mon, 21 Feb 2011 18:51:50 +0000 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=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Roberto Spadim Cc: Phillip Susi , David Brown , linux-raid@vger.kernel.org List-Id: linux-raid.ids (please don't top post) On 21 February 2011 18:25, Roberto Spadim wrote= : > TRIM is a new feature for many hard disk/ssd > it=C2=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. =C2=A0It seems that the= days of >>> TRIM may well be numbered - the latest generation of high-end SSDs = have >>> more powerful garbage collection algorithms, together with more spa= re >>> blocks, making TRIM pretty much redundant. =C2=A0This is, of course= , the most >>> convenient solution for everyone (as long as it doesn't cost too mu= ch!). >>> >>> The point of the TRIM command is to tell the SSD that a particular = block >>> is no longer being used, so that the SSD can erase it in the backgr= ound >>> - that way when you want to write more data, there are more free bl= ocks >>> ready and waiting. =C2=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. =C2=A0Whe= n doing >> wear leveling, you might find an erase block that has not been writt= en >> to in a long time, so you want to move that data to a more worn bloc= k, >> and use the less worn block for more frequently written to sectors. = =C2=A0If >> 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 = to >> 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 =C2=A0http://vger.kernel.org/majordomo-info.h= tml >> > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > -- > 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 =C2=A0http://vger.kernel.org/majordomo-info.ht= ml > TRIM is not a new feature for HDDs as they don't have the problem that SSDs have. Where did you hear this? // Mathias -- 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