I do a disk check once in a while, and today I found a nice surprise:
http://i618.photobucket.com/albums/tt267/knewbee21/bad-disk_zps8491a739.png
http://i618.photobucket.com/albums/tt267/knewbee21/bad-disk_zps8491a739.png
dd
to copy the entire partition to another drive (smaller & slower) but just in case the current one decides to die.wblock@ said:The reallocated sector count starts increasing when the drive finds a bad block on write. A drive that starts growing new bad blocks might work for another five years, or might fail in hours. Don't trust such a drive.
dd
and check the values before and after. Drives with no bad blocks at all, those I have not seen for ages. dd if=/dev/ada0 of=/dev/ada0
on an unmounted drive, reading each sector and rewriting it to the same place. This should get the drive to find bad blocks without the help of ZFS, maybe it even can prevent some bad blocks by reading and rewriting them before they detoriate too much for the error correction in the firmware to fail them. If anyone knows more about this, or has used that method, I would like to hear some experience.Crivens said:But sadly all new drives come with bad blocks already, so these numbers are most likely never zero. When you get a new drive, be sure to write it completely usingdd
and check the values before and after.
smartctl -t long /dev/ada0
) seems to test every block. It takes about the same amount of time as a dd
to every block, anyway.