Changes between Version 22 and Version 23 of BadBlockHowto

Timestamp:

May 24, 2018, 7:19:44 PM (6 years ago)

Author:

jinn

Comment:

Added reference to use hdparm when dd is unable to force the sector reallocation.

BadBlockHowto

@@ -165 +165 @@
 root]# dd if=/dev/zero of=/dev/hda3 bs=4096 count=1 seek=2269012
 root]# sync
+}}}
+
+On some occasions using `dd` may not result in the sector being reallocated, with an error along the following lines:
+
+{{{
+May 24 14:19:30 ht-xm-2 kernel: ata1.00: exception Emask 0x0 SAct 0x8000000 SErr 0x0 action 0x0
+May 24 14:19:30 ht-xm-2 kernel: ata1.00: irq_stat 0x40000008                                  
+May 24 14:19:30 ht-xm-2 kernel: ata1.00: failed command: READ FPDMA QUEUED                    
+May 24 14:19:30 ht-xm-2 kernel: ata1.00: cmd 60/08:d8:08:16:00/00:00:01:00:00/40 tag 27 ncq dma 4096 in
+     res 41/40:08:0a:16:00/00:00:01:00:00/00 Emask 0x409 (media error) <F>                                                                                                            
+May 24 14:19:30 ht-xm-2 kernel: ata1.00: status: { DRDY ERR }                                 
+May 24 14:19:30 ht-xm-2 kernel: ata1.00: error: { UNC }                                       
+May 24 14:19:30 ht-xm-2 kernel: ata1.00: configured for UDMA/133                              
+May 24 14:19:30 ht-xm-2 kernel: sd 0:0:0:0: [sda] tag#27 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
+May 24 14:19:30 ht-xm-2 kernel: sd 0:0:0:0: [sda] tag#27 Sense Key : Medium Error [current]   
+May 24 14:19:30 ht-xm-2 kernel: sd 0:0:0:0: [sda] tag#27 Add. Sense: Unrecovered read error - auto reallocate failed
+May 24 14:19:30 ht-xm-2 kernel: sd 0:0:0:0: [sda] tag#27 CDB: Read(16) 88 00 00 00 00 00 01 00 16 08 00 00 00 08 00 00
+May 24 14:19:30 ht-xm-2 kernel: blk_update_request: I/O error, dev sda, sector 16782858       
+May 24 14:19:30 ht-xm-2 kernel: Buffer I/O error on dev sda, logical block 2097857, async page read
+May 24 14:19:30 ht-xm-2 kernel: ata1: EH complete
+}}}
+
+In this case you may have better success using the `hdparm` tool.  First confirm the read error on the sector, which would look like this for the above error:
+
+{{{
+# hdparm --read-sector 16782858 /dev/sda
+}}}
+
+And when you've confirmed the sector is indeed unreadable, use `hdparm` to write to that sector:
+
+{{{
+# hdparm --write-sector 16782858 /dev/sda
 }}}
 
@@ -340 +372 @@
 [root]# dd if=/dev/zero of=/dev/hda bs=512 count=17 seek=35495735
 }}}
+
+If using `dd` doesn't result in a reallocation, you may have better luck using `hdparm` as documented in the first example on this page.
 
 At this point we now have: