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About a week ago my Windows 7 PC got progressively slower over a day or two before it got the point where it was unusable. Everything would pretty much freeze when trying to even carry out the most mundane of tasks (i.e browsing the web). When I attempted to run a virus scan, I noticed the read/write speeds were really slow, and the same when I was deleting/transferring files on the hide drive.

I subsequently thought there may be a hard drive problem, but nonetheless I tried a clean OS install, and everything worked fine. A few days later, suddenly everything locked up on me again. At one point it failed to boot, launching the windows boot recovery (I can't remember the exact name - launched because windows failed to start up), which itself couldn't start, showing me a black & white screen saying that the hard disk may be failing.

I've since run an Ubuntu live CD and run a SMART scan on the hard drive, but I'm not sure how to digest the results (see below). There's a tonne of stuff about Pre-fail and Old_age so I would assume it's time to buy a new hard drive, but I'd be really appreciative if someone could tell me exactly what this info means and whether or not I'm correct.

SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x85) Offline data collection activity
                    was aborted by an interrupting command from host.
                    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:        (11160) seconds.
Offline data collection
capabilities:            (0x7b) SMART execute Offline immediate.
                    Auto Offline data collection on/off support.
                    Suspend Offline collection upon new
                    Offline surface scan supported.
                    Self-test supported.
                    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:    (   2) minutes.
Extended self-test routine
recommended polling time:    ( 131) minutes.
Conveyance self-test routine
recommended polling time:    (   5) minutes.
SCT capabilities:          (0x303f) SCT Status supported.
                    SCT Error Recovery Control supported.
                    SCT Feature Control supported.
                    SCT Data Table supported.

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
  1 Raw_Read_Error_Rate     0x002f   200   200   051    Pre-fail  Always       -       0
  3 Spin_Up_Time            0x0027   170   160   021    Pre-fail  Always       -       4483
  4 Start_Stop_Count        0x0032   098   098   000    Old_age   Always       -       2144
  5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x002e   100   253   000    Old_age   Always       -       0
  9 Power_On_Hours          0x0032   076   076   000    Old_age   Always       -       17749
 10 Spin_Retry_Count        0x0032   100   100   000    Old_age   Always       -       0
 11 Calibration_Retry_Count 0x0032   100   100   000    Old_age   Always       -       0
 12 Power_Cycle_Count       0x0032   098   098   000    Old_age   Always       -       2014
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       156
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       2144
194 Temperature_Celsius     0x0022   110   103   000    Old_age   Always       -       37
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   200   200   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       368039
200 Multi_Zone_Error_Rate   0x0008   200   200   000    Old_age   Offline      -       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  Extended offline    Completed without error       00%     17749         -

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.

Additional device info:

Model Family:     Western Digital Caviar Blue Serial ATA
Device Model:     WDC WD6400AAKS-00A7B2
User Capacity:    640,135,028,736 bytes [640 GB]
Sector Size:      512 bytes logical/physical

marked as duplicate by Carl B, Dave M, Nifle, Ƭᴇcʜιᴇ007, Shekhar Sep 1 '13 at 16:45

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • 1
    You have multiple failures. I would replace the HDD. – Ramhound Aug 21 '13 at 18:21
  • Can you give more information about the HDD? Capacity, manufacturer, whether it is an SSD (maybe it's the most relevant part). Have you tried to defragment the drive? If it is an SSD don't defrag. – Doktoro Reichard Aug 21 '13 at 18:58
  • Thanks CarlB and Ramhound @DoktoroReichard I did try and defrag prior to the wipe but everything was so slow it wasn't really feasible. The drive is not an SSD. Added more info to post. – AaronDS Aug 21 '13 at 20:58
  • 1
    You don't need to post more information. Your hdd is failing your Reallocated_Event_Count is high and you are failing 2 other tests. There is nothing you can do besides replace the drive. – Ramhound Aug 21 '13 at 21:00
  • Ok great thanks @Ramhound, thought I would provide as requested anyway. Feel free to add as answer and I'll accept. – AaronDS Aug 21 '13 at 21:01

The disk seems good to me. "Pre-Fail" attributes are those that, if below (or equal to) threshold, may indicate pre-failure (imminent disk failure). "Old age" attributes are the ones that indicate normal wear and tear.

So, a reallocated event count of 200/200 with threshold 000 ought to mean "No reallocated events", i.e., "No errors".

This is what I read on my home unit:

  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always       -       1
 10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       3
 12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       105
184 End-to-End_Error        0x0032   100   100   099    Old_age   Always       -       0
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
188 Command_Timeout         0x0032   100   096   000    Old_age   Always       -       4295098559
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

As you can see, I got a sluggish command timeout sometime or other, but the other parameters are (touch wood!) read from a healthy disk.

See also here.

Anyway, check out Windows Event Viewer (eventvwr). If the hard disk has problems, even if they are not reported by SMART, you ought to see something in the event log relating to disk errors, or maybe filesystem errors. If you see nothing of the kind, you of course still have some problem - the system didn't slow down by itself! - but they are not disk problems.

For example, once I experienced similar symptoms (only much worse). The hard disk was working... then sometimes it would log "hardware disk errors" that the SMART wasn't seeing at all. Windows signaled "Delayed write failed, data might have been lost" (and now that I come to think of it: did you see that message popping up? If the hard disk is going, you should have). I removed the disk and connected to another computer to run some tests. Everything worked. Sheesh. So I put the disk back. But this time it kept working perfectly. Only then I remembered that reconnecting the disk had felt much harder than disconnecting had been -- just as if the connector was already partially loose. It might be worth it to check.

Else, you might be interested in some tool such as Auslogics' BoostSpeed. It's not perfect (it falls for the .wid btrez.dll 'error' - but it's fixable and there's a workaround) and it falls a bit on the scaremongering side when it reports any registry anomaly as a sign of impending doom, but it does its work, and IMHO it's worth the money.

Just to be sure, you can download an ISO of some antivirus - Kaspersky has a free version, and there are others -, boot from that, and make sure you're not slowed down by some unwanted "guest".

But before doing anything else, however, backup all your valuable data on an external device. That way, whatever it is happening, they ought to be safe.

  • Thanks, interesting read. I went ahead and replaced the hard disk before seeing this and so far I haven't had any problems. – AaronDS Aug 26 '13 at 23:09

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