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[irha]

My DNS-321 is showing "Abnormal" status for one of the drives in a RAID-1 configuration and it is a bit confusing which drive is failing. Under hard sdrive info, I see something like this:

Right WDC: ... Normal
Left WDC: ... Abnormal

When I click on "Abnormal", I get a report that says:
Item    Now     Worst   Thresh  Updated
1       Raw_Read_Error_Rate     1       1       51      302541
3       Spin_Up_Time    110     107     21      7466
4       Start_Stop_Count        100     100     0       247
5       Reallocated_Sector_Ct   200     200     140     0
7       Seek_Error_Rate 200     200     0       0
9       Power_On_Hours  99      99      0       825
10      Spin_Retry_Count        100     100     0       0
11      Calibration_Retry_Count 100     253     0       0
12      Power_Cycle_Count       100     100     0       26
192     Power-Off_Retract_Count 200     200     0       19
193     Load_Cycle_Count        200     200     0       278
194     Temperature_Celsius     108     102     0       39
196     Reallocated_Event_Count 200     200     0       0
197     Current_Pending_Sector  192     192     0       1458
198     Offline_Uncorrectable   192     192     0       1402
199     UDMA_CRC_Error_Count    200     200     0       0
200     Multi_Zone_Error_Rate   185     184     0       3178


What exactly is abnormal here? For comparison, I clicked on the "Normal" button and this is what I see:
Item    Now     Worst   Thresh  Updated
1       Raw_Read_Error_Rate     200     200     51      0
3       Spin_Up_Time    168     164     21      6600
4       Start_Stop_Count        100     100     0       257
5       Reallocated_Sector_Ct   200     200     140     0
7       Seek_Error_Rate 200     200     0       0
9       Power_On_Hours  90      90      0       7589
10      Spin_Retry_Count        100     100     0       0
11      Calibration_Retry_Count 100     253     0       0
12      Power_Cycle_Count       100     100     0       26
192     Power-Off_Retract_Count 200     200     0       9
193     Load_Cycle_Count        200     200     0       257
194     Temperature_Celsius     115     106     0       35
196     Reallocated_Event_Count 200     200     0       0
197     Current_Pending_Sector  200     200     0       0
198     Offline_Uncorrectable   200     200     0       0
199     UDMA_CRC_Error_Count    200     200     0       0
200     Multi_Zone_Error_Rate   200     200     0       0

Looks like the one which is supposed to be normal has a very high Raw_Read_Error_Rate, where as the one that is supposed to be abnormal, has only a value of 1. So which one is actually failing? Also, would the  "Left WDC" drive be the top or bottom drive? I guess I can pull one of the drives out and match the s/no, but I am not even sure if DNS-321 is giving accurate information.

[jamieburchell]

The drive you say is "abnormal" in your post has

1       Raw_Read_Error_Rate     1       1       51      302541
198     Offline_Uncorrectable   192     192     0       1402
200     Multi_Zone_Error_Rate   185     184     0       3178

What do you mean top and bottom drives? They are installed left to right?

[irha]

The drive you say is "abnormal" in your post has

1       Raw_Read_Error_Rate     1       1       51      302541
198     Offline_Uncorrectable   192     192     0       1402
200     Multi_Zone_Error_Rate   185     184     0       3178

I looked at a reference http://www.z-a-recovery.com/man-smart.htm, but I am still a bit confused on how to interpret these numbers. So in general, a lower number means it is bad? Is 200 considered a good reference number, and anything lower than that might indicate a failure?

Edit: I jumped to relevant information without reading at the beginning, and I see that the link already answers my above question. It basically says: "on the scale from 0 (bad) to some maximum (good) value. Maximum values are typically 100, 200 or 253. Rule of thumb is: high values are good, low values are bad.". I now understand what these numbers indicate.

What do you mean top and bottom drives? They are installed left to right?

You are right, I think I was confused because I had Corza for a few days before replacing it with the D-Link, and it had drives one over the other.

Thanks for your help.

[jamieburchell]

Actually it's my understanding that the last column of values are that of interest and that the higher the error values, the "worse" it is. I.e. 302541

In any case, the abnormal drive has defective sectors so I would consider replacing it.

[irha]

Actually it's my understanding that the last row of values are that of interest and that the higher the error values, the "worse" it is. I.e. 302541

In any case, the abnormal drive has defective sectors so I would consider replacing it.

Thanks for the clarification.

PS: I guess you mean last column of values.

[irha]

I already requested for an RMA advance replacement from WD, but wondering if I should something immediately right now. Is it better to emove the one that is reported abnormal in advance and use it with the one drive or should I leave it in there? Also, is it better to keep the NAS shutdown until I get the replacement?

[jamieburchell]

Yes I meant column
I would backup your data somewhere if possible. Not sure about your other questions. I'd probably leave it in, it hasn't totally failed yet and two up to date copies is better than one.

[jamieburchell]

You're right about higher normalised values being good and that they shouldn't be lower than the threshold. If those column headings are correct, the first row (error rate) means the drive is failing as the normalised value is 1 and is less than the threshold. There's also an indication of bad sectors.

[irha]

Thanks jamieburchell!

I am also wondering if one of the drives failing could cause the read speeds to go down drastically. Currently, the read speeds vary anywhere from just a few kb to sometimes up to 10mb/s and is very unpredictable. I actually never got good speeds with this NAS (mostly an average of 2.5 to 3mb/s) but didn't have time to diagnose until now. So far I verified that the connections from my PC and DNS321 to the gigabit switch are in deed at gigabit speed (my switch lights two leds if the speed is gigabit), so looks like the problem is not with the networking and could be due to the bad disk all along.

[jamieburchell]

Yes it could be, what with the read error rate being so high. If you did pull the bad disk out you might see the speed improve but I don't know that for sure.

[irha]

I got my replacement drive and put the drive in after shutting down the NAS. During the startup, the NAS took me through a couple of pages to initialize the drive and the process was stuck with the formatting progress bar at 0% and the NAS is unresponsive to web UI or ssh. I waited over night and it is the same, so I restarted the NAS using the power switch and but the same behavior repeats (ie., the same wizard at the startup and the same unresponsiveness later). What is going wrong here? I would appreciate any help. Thanks

[jamieburchell]

Try a factory reset first me thinks.
Are you also certain that you replaced the correct drive? Which drive did you go for? Have you tried checking the drive with the manufacturers diagnostics to ensure it's healthy?

[irha]

I replaced the left side one, and confirmed the s/no to be the same as the one I RMA'ed. I didn't test the drive, but I am sure the one inside is the one reported as "Normal". Could doing a factory reset make the NAS forget how to rebuild the array? If the only option after a reset is to build a fresh array together, then that would cause a loss of my data, so I am a little worried.

[gunrunnerjohn]

A factory reset should not lose the data, I've done that exact procedure with a RAID-1 array.

[irha]

OK, I went ahead and did a factory reset and logged in with no password. I got the same screen, but I skipped and went into the status and verified the status. I then went into Raid page and opted to rebuild the raid-1 array and it is now stuck at the same screen as before. The device is now unresponsive. One thing I failed to mention is that in this state, I don't see any drive activity (as per the leds) taking place. Here is a screenshot of this screen: