From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: SSD - TRIM command Date: Mon, 21 Feb 2011 22:46:34 -0300 Message-ID: References: <4D62CF5F.6080007@cfl.rr.com> <20110222003610.GB29101@bounceswoosh.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110222003610.GB29101@bounceswoosh.org> Sender: linux-raid-owner@vger.kernel.org To: "Eric D. Mudama" Cc: =?ISO-8859-1?Q?Mathias_Bur=E9n?= , Phillip Susi , David Brown , linux-raid@vger.kernel.org List-Id: linux-raid.ids if it make sense on ssd, harddisk make sense too, it's a block device like ssd, the diference of ssd/harddisk? access time, bytes(bits)/block, life time bad block exist in ssd and harddisk, ssd can realloc online, some hardd= isks too > no, because the host may immediately write to a trim'd sector yes, filesystem know where exists a unused sector if device (harddisk/ssd) know and have a reallocation algorithm, it can realloc without telling filesystem to do it (that's why TRIM is interesting) since today ssd use NAND (not NOR) the block size isn't 1 bit like a harddisk head. trim for harddisk only make sense for badblock reallocation -------------------------- getting back to the first question, can MD support trim? yes/no/not now/some levels and layouts only? 2011/2/21 Eric D. Mudama : > On Mon, Feb 21 at 20:52, Roberto Spadim wrote: >> >> trim tell harddisk that those block are not in use > > yes > >> not in use block can be used by harddisk reallocation algorithm, lik= e >> spare sectors > > no, because the host may immediately write to a trim'd sector > > The spares in an HDD can never be accessed outside of special tools, > they're swap-in replacements for regions of the media that have > developed defects. > >> hard disks can use TRIM command to 'create' 'good' blocks like spare >> sectors > > this doesn't make sense to me > > > -- > Eric D. Mudama > edmudama@bounceswoosh.org > > -- > 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