Andy Smith <[email protected]> writes: > I suppose it is possible that you have a drive that doesn't report > reallocated sectors properly.
I wonder how common that is? I have this old drive (not in actual use) where some six sectors sometimes become unreadable and this causes for example the SMART long test to fail and Linux logs things like this when trying to read the sectors: kernel: sd 0:0:0:0: [sda] tag#11 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s kernel: sd 0:0:0:0: [sda] tag#11 Sense Key : Medium Error [current] kernel: sd 0:0:0:0: [sda] tag#11 Add. Sense: Unrecovered read error - auto reallocate failed kernel: sd 0:0:0:0: [sda] tag#11 CDB: Read(16) 88 00 00 00 00 02 0a e6 eb 90 00 00 00 08 00 00 kernel: I/O error, dev sda, sector 8772840336 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2 kernel: Buffer I/O error on dev sda2, logical block 364039538, async page read But SMART Reallocated_Event_Count stays at 0. So I have to wonder if it used up all its remappable sectors already or what's going on. The oft-referred web page mentioned in this thread too also noted this, that an unreadable sector isn't necessarily remapped, possibly because it's writable so the drive FW doesn't care. Or the drive is just keeping mum about what's going on. One hint towards the drive lying could be that the LBA number reported by SMART isn't the same as what the actual failing sector is when reading the sector via dd or hdparm. But I don't really know how the LBAs are mapped to what these userland tools see. The drive is a WD60EFRX-68L0BN1 according to hdparm.
