Re: Need urgent help in fixing raid5 array

[Mike Myers <mikesm559@yahoo.com>]

BTW, here is the smart error listing for one of the devices that md seems to refuse to add:

 smartctl -l error  /dev/sdb1
smartctl 5.39 2008-05-08 21:56 [x86_64-unknown-linux-gnu] (local build)
Copyright (C) 2002-8 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF READ SMART DATA SECTION ===
SMART Error Log Version: 1
ATA Error Count: 1
        CR = Command Register [HEX]
        FR = Features Register [HEX]
        SC = Sector Count Register [HEX]
        SN = Sector Number Register [HEX]
        CL = Cylinder Low Register [HEX]
        CH = Cylinder High Register [HEX]
        DH = Device/Head Register [HEX]
        DC = Device Command Register [HEX]
        ER = Error register [HEX]
        ST = Status register [HEX]
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.

Error 1 occurred at disk power-on lifetime: 6388 hours (266 days + 4 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 00 00 00 00 a0

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  ec 00 00 00 00 00 a0 08   6d+23:19:44.200  IDENTIFY DEVICE
  25 00 01 01 00 00 00 04   6d+23:19:44.000  READ DMA EXT
  25 00 80 be 1b ba ef ff   6d+23:19:42.500  READ DMA EXT
  25 00 c0 7f 1b ba e0 08   6d+23:19:42.500  READ DMA EXT
  25 00 40 3f 1b ba e0 08   6d+23:19:30.300  READ DMA EXT


It looks like a good disk.

thx
mike




----- Original Message ----
From: Justin Piszcz <jpiszcz@lucidpixels.com>
To: Mike Myers <mikesm559@yahoo.com>
Cc: linux-raid@vger.kernel.org; john lists <john4lists@gmail.com>
Sent: Friday, January 2, 2009 10:57:13 AM
Subject: Re: Need urgent help in fixing raid5 array



On Fri, 2 Jan 2009, Mike Myers wrote:

> Well, I can read from sdg1 just fine.  It seems to work ok, at least for a few GB of data.   I'll try this on some of the other disks, but it is possible for to pull the disks out of the backplane and run the SFF-8087 fanout cables direct to each drive and bypass the backplane completely.  It certainly would be easy to do this for the at least the sdo1 drive and see if I can get better results going direct to the disk.  I have moved the disks around the backplane a bit to deal with the issues of the controller failure, so I am pretty sure it's not just one bad slot or the like.
> 
> So you've seen a backplane fail in away that the disks come up fine at boot but have corrupted data transfers across them?  I wonder about the sata cables in that case as well.  I could hook up a pair of PMP's to my SI3132's and bypass the 8077 cables as well.

1. Try by-passing the backplane.
2. Bad cables will usually cause smart identifier UDMA_CRC_Error_Count to
   increase quite high, if it is 0 or close to it, the cable is unlikely the
   issue.
3. I have seem all kinds of weirdness with bad backplanes, drives dropping out
   of the array, drives producing I/O errors, etc.

Justin.

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