Return-Path: Received: from mail.virtall.com ([178.63.195.102]:51360 "EHLO mail.virtall.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752737AbaLEKDI (ORCPT ); Fri, 5 Dec 2014 05:03:08 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Date: Fri, 05 Dec 2014 11:03:03 +0100 From: Tomasz Chmielewski To: linux-btrfs Cc: lists@colorremedies.com Subject: Re: btrfs device delete missing - Input/output error Message-ID: <3146bf116f41e590e8ce4fdb610def31@admin.virtall.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: > The first way to try to recover the current volume would be to > overwrite LBA 2262535088 which you should only do with the filesystem > unmounted. That's the sector causing the read error. If this is a 512 > byte drive: > > dd if=/dev/zero of=/dev/sdb count=1 seek=2262535088 It is a 512 byte drive. Unfortunately overwriting that fails - which is quite weird, given that there are 0 reallocated sectors, according to SMART. Is there a way to determine what's stored there (i.e. if it's a file?). # dd if=/dev/zero of=/dev/sdb count=1 seek=2262535088 dd: writing to `/dev/sdb': Input/output error 1+0 records in 0+0 records out 0 bytes (0 B) copied, 2.88439 s, 0.0 kB/s # dmesg -c [ 8177.713212] ata4.00: exception Emask 0x0 SAct 0x400 SErr 0x0 action 0x0 [ 8177.713285] ata4.00: irq_stat 0x40000008 [ 8177.713349] ata4.00: failed command: READ FPDMA QUEUED [ 8177.713419] ata4.00: cmd 60/08:50:b0:8b:db/00:00:86:00:00/40 tag 10 ncq 4096 in [ 8177.713419] res 41/40:08:b0:8b:db/00:00:86:00:00/00 Emask 0x409 (media error) [ 8177.713662] ata4.00: status: { DRDY ERR } [ 8177.713725] ata4.00: error: { UNC } [ 8177.755099] ata4.00: configured for UDMA/133 [ 8177.755175] sd 3:0:0:0: [sdb] [ 8177.755252] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [ 8177.755318] sd 3:0:0:0: [sdb] [ 8177.755380] Sense Key : Medium Error [current] [descriptor] [ 8177.755449] Descriptor sense data with sense descriptors (in hex): [ 8177.755516] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00 [ 8177.755600] 86 db 8b b0 [ 8177.755667] sd 3:0:0:0: [sdb] [ 8177.755729] Add. Sense: Unrecovered read error - auto reallocate failed [ 8177.757316] sd 3:0:0:0: [sdb] CDB: [ 8177.757377] Read(16): 88 00 00 00 00 00 86 db 8b b0 00 00 00 08 00 00 [ 8177.757463] end_request: I/O error, dev sdb, sector 2262535088 [ 8177.757542] ata4: EH complete -- Tomasz Chmielewski http://www.sslrack.com