<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Wed, Jul 23, 2014 at 12:41 PM, John Drescher <span dir="ltr"><<a href="mailto:drescherjm@gmail.com" target="_blank">drescherjm@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="">>>BTW, what causes a drive to just disappear until a hard reboot?<br>
><br>
> All sorts of things can cause that. You can blame a passing cosmic<br>
> ray, if you feel like it. A cosmic ray hit in many types of buffer<br>
> circuit can cause the circuit to lock into a single state and be<br>
> unable to switch states until the substrate power is removed for a<br>
> while. If the buffer is one in the path that commands take to the<br>
> disk, a stuck bit like that can easily stop it responding at all until<br>
> a power cycle. Static electricity can do the same, either a discharge<br>
> or a field effect from moving something too near that has a big charge<br>
> on it. So a drive that stops responding once like that may never do<br>
> it again. Or it may be a sign of a real problem and it is going to do<br>
> it again very soon.<br>
><br>
<br>
</div>Take a look at the SMART raw data. Are there any pending or offline<br>
uncorrectable sectors? How many reallocated sectors? Reallocation<br>
events? UltraDMA ECC errors?<br>
<span class=""></span><br></blockquote></div><br><br>ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE<br> 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0<br>
3 Spin_Up_Time 0x0027 253 253 021 Pre-fail Always - 1025<br> 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 57<br> 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0<br>
7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0<br> 9 Power_On_Hours 0x0032 061 061 000 Old_age Always - 28498<br> 10 Spin_Retry_Count 0x0032 100 253 000 Old_age Always - 0<br>
11 Calibration_Retry_Count 0x0032 100 253 000 Old_age Always - 0<br> 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 55<br>192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 31<br>
193 Load_Cycle_Count 0x0032 001 001 000 Old_age Always - 1007725<br>194 Temperature_Celsius 0x0022 113 105 000 Old_age Always - 37<br>196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0<br>
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0<br>198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0<br>199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0<br>
200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0<br></div></div>