Re: disk bad block
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. 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 tried to summarize this here: http://caoua.org/alex/obsd/badsect.html -- Alexandre
Re: disk bad block
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.
disk bad block
Hi misc, 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 ? One solution is to create two partitions without the bad block and use ccd. Is there another solution ? And is there any way to isolate some bad blocks on an existing partition? I know that I should buy another disk :-) Thanks Paulo Manoel Mafra LCMI - Laboratorio de Controle e Micro Informatica Departamento de Automagco e Sistemas - UFSC
Re: disk bad block
Paulo Manoel Mafra wrote: Hi misc, 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 ? One solution is to create two partitions without the bad block and use ccd. Is there another solution ? And is there any way to isolate some bad blocks on an existing partition? Somehow create a file which occupies those blocks. Preferably including neighboring blocks. Do not EVER delete or use the file. I know that I should buy another disk :-) Yes, it almost certainly has other problems. For a long time, drives will show a bad sector only when the hardware has run out of spares in the neighborhood. When it shows a bad block, there is more that one problem already on the disk. Probably useful as a learning experience watching a disk slowly go bad. However you do not want to put your only copy of anything important on it. Thanks Paulo Manoel Mafra LCMI - Laboratorio de Controle e Micro Informatica Departamento de Automagco e Sistemas - UFSC
Re: disk bad block
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. One solution is to create two partitions without the bad block and use ccd. Is there another solution ? badsect(8) if your data is worth nothing.
