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 harddisks 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 <edmudama@xxxxxxxxxxxxxxxx>: > 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, like >> 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@xxxxxxxxxxxxxxxx > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
