Hi, > On Wed, May 03, 2006 at 04:17:57PM +0100, Stuart Henderson wrote: >> On 2006/05/03 10:24, Paulo Manoel Mafra wrote: >> > I would like to create a large partition on a disk, but this disk has >> a >> > known bad block. How could I create the partition without the bad >> block ? >> >> Use a different drive? It's normal for drives to have bad blocks, >> they used to be printed on a label attached to the drive, modern drives >> have spare capacity which is automatically allocated over bad or failing >> blocks. If this isn't happening any more, the drive is not worth >> trusting. nope. normal IDE/SATA drives have an "Non Recoverable Read Error Rate" of 1 per 10^14 bits. which could be translated into 1 bad sector for each 12.5 Terrabytes read. Good SCSI-Disks and some SATA drives have 10^15 or 10^16. Which resolves into 1 per 125 or 1250 Terrabytes.
This is more or less confirmed by the drive error-failure rates I observed on a bunch of servers. We are having around 1 disk failing with one bad sector or a small cluster of bad sectors per month. we just reinit the raid and that's it. Of course if a drive does that more then once in a while get's swapped. So from out point of view they still are to be trusted, if you don't trust them because of that you have to switch to SCSI or maybe Raptors but no other IDE/SATA drive. The times were you had "error free" drives are over for the moment. Unless manufacturers decide in favor of less storage density and therefore lower bad sector rate as they do with SCSI drives. Which is unlikely since the normal end-user will never notice this problem. We tried replacing some IDE drives with new drives from maxtor which claim to have 10^15, but since their bugridden firmware gives us CRC errors in SATA mode even during OS install we dropped them and will stay with Samsung, which have better support and replacement _and_ a Jumper to get them down into 1.5G mode. > i've got a drive that sometimes fails to replace bad blocks even if > there seems to be spare blocks available unless i overwrite them. I've that's the way it should be. in case there is something really important in this sector I do not wan't it to be erased before I can send the drive to someone who can recover the data which the drive can't recover itself. bye, siggi.
