"ad0: TIMEOUT - WRITE_DMA" type errors with 7.0-RC1

Jeremy Chadwick koitsu at FreeBSD.org
Fri Jan 25 17:21:24 PST 2008

On Fri, Jan 25, 2008 at 06:03:33PM -0700, Joe Peterson wrote:
> Wow, pretty crazy!  Hmm, and yes, those LBAs do look close together.
> Well, let me know how the smartctl output looks.  I'd be curious if your
> bad sector count rises.

Absolutely nada on the SMART statistics.  Nothing incremented or changed
in any way.  My short and long tests did not change any of the data in
the fields either.  Full output is below my .sig.

> BTW, I tried:
> crater# dd if=/dev/ad1s4 of=/dev/null bs=64k
> ^C1408596+0 records in
> 1408596+0 records out
> 92313747456 bytes transferred in 1415.324362 secs (65224446 bytes/sec)
> (I let it go for 92GB or so) - no messages about ad1.  So I wonder if
> this points at either the cable connector on ad0 or the drive itself.  I
> guess I'd rather have a failing drive than motherboard...
> I originally was wondering if somehow something peculiar about ZFS's
> disk access pattern was making it happen...

Since I'm used to dealing with disk issues (at work and personally), I'm
left wondering if this is some strange ATA subsystem quirk, or
ultimately something with ZFS (your "something peculiar about ZFS's disk
access pattern" claim is starting to look more plausible).

This may sound suicidal, but I'm hoping to recreate the scenario
somehow, and then punt the details to Soren or Xin Li for further
investigation -- if it looks like an ATA subsystem thing, that is.

It is interesting to note that we both have Seagate disks...  :-) I'll
have to run SeaTools on my disk to see if anything comes back, or run a
selective LBA test in smartctl (since the drive supports it).

I've restarted my rsync since, and it's happily chomping away without an
issue.  If my problem was TRULY a bad block or something causing
mechanical lock-up on the disk, I'd have expected my latest rsync to
induce it.

There's always the chance of some bizarre drive firmware bug too.

> THanks for the recomendations.  I'll keep an eye on it, and I'll let you
> know what a cable change does for me.  Still, I have not had any ad0
> messages since this morning (I haven't been using the system today much,
> but maybe the cron processes are more likely to trigger it...

Understood.  In my case, I *know* the cables are fine, because the box
itself I just built and migrated to a few days ago (change of
motherboard, chassis, and addition of SATA hot-swap backplane).  We use
the same motherboard (Supermicro PDSMI+) in all of our production
servers in our datacenter, and they're rock-solid.

I've done hot-swapping without any issue on those systems too, and I've
never seen any SATA system issues -- one of the systems is our
datacenter backup server, which holds nightly backups for all the other
boxes (about 6).  Due to the heavy disk I/O that occurs for hours at a
time, if this was some weird system quirk, motherboard problem, or SATA
bus/cable issue, we would've seen it by now.  FWIW: all our systems,
including the backup box, use UFS2 exclusively -- no ZFS in the picture.

| Jeremy Chadwick                                    jdc at parodius.com |
| Parodius Networking                           http://www.parodius.com/ |
| UNIX Systems Administrator                      Mountain View, CA, USA |
| Making life hard for others since 1977.                  PGP: 4BD6C0CB |

icarus# smartctl -a /dev/ad6
smartctl version 5.37 [i386-portbld-freebsd7.0] Copyright (C) 2002-6 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

Model Family:     Seagate Barracuda 7200.10 family
Device Model:     ST3500630AS
Serial Number:    9QG1YWNL
Firmware Version: 3.AAE
User Capacity:    500,107,862,016 bytes
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   7
ATA Standard is:  Exact ATA specification draft version not indicated
Local Time is:    Fri Jan 25 17:10:31 2008 PST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x82) Offline data collection activity
                                        was completed without error.
                                        Auto Offline Data Collection: Enabled.
Self-test execution status:      (   0) The previous self-test routine completed
                                        without error or no self-test has ever
                                        been run.
Total time to complete Offline
data collection:                 ( 430) seconds.
Offline data collection
capabilities:                    (0x5b) SMART execute Offline immediate.
                                        Auto Offline data collection on/off support.
                                        Suspend Offline collection upon new
                                        Offline surface scan supported.
                                        Self-test supported.
                                        No Conveyance Self-test supported.
                                        Selective Self-test supported.
SMART capabilities:            (0x0003) Saves SMART data before entering
                                        power-saving mode.
                                        Supports SMART auto save timer.
Error logging capability:        (0x01) Error logging supported.
                                        General Purpose Logging supported.
Short self-test routine
recommended polling time:        (   1) minutes.
Extended self-test routine
recommended polling time:        ( 163) minutes.

SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
  1 Raw_Read_Error_Rate     0x000f   114   094   006    Pre-fail  Always       -       131599973
  3 Spin_Up_Time            0x0003   094   094   000    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       6
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000f   082   060   030    Pre-fail  Always       -       200325271
  9 Power_On_Hours          0x0032   097   097   000    Old_age   Always       -       2970
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       9
187 Unknown_Attribute       0x0032   100   100   000    Old_age   Always       -       0
189 Unknown_Attribute       0x003a   100   100   000    Old_age   Always       -       0
190 Temperature_Celsius     0x0022   063   050   045    Old_age   Always       -       773849125
194 Temperature_Celsius     0x0022   037   050   000    Old_age   Always       -       37 (Lifetime Min/Max 0/29)
195 Hardware_ECC_Recovered  0x001a   062   059   000    Old_age   Always       -       5882952
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0010   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x003e   200   200   000    Old_age   Always       -       0
200 Multi_Zone_Error_Rate   0x0000   100   253   000    Old_age   Offline      -       0
202 TA_Increase_Count       0x0032   100   253   000    Old_age   Always       -       0

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%      2970         -
# 2  Short offline       Completed without error       00%       321         -

SMART Selective self-test log data structure revision number 1
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.

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