On a leased server, I am running into some timing issues with an application that requires precise timing. Server is a Dual Xeon E5410 running on a Supermicro X7DVL-3 motherboard under CentOs 5.5 x64. The application I am running is timer sensitive and keeps sensing drift whether under load or at idle, but especially under load. I did some investigating with atop and dd and found some mind-blowing numbers. Mind you, I am no Linux guru but something sure seems out of whack. I ran: dd bs=4096 if=/dev/zero of=/bigtestfile to generate disk activity. Regardless whether I wrote it to sda or sdb my DSK value in atop would go over 100%, at one time peaking at 1700%. Again it does not matter if I am writing to sda or sdb. DSK | sdb | busy 675% | read 0 | write 110 | avio 78 ms | Here are the smartctl outputs: # smartctl -A /dev/sda smartctl version 5.38 [x86_64-redhat-linux-gnu] Copyright (C) 2002-8 Bruce Allen Home page is http://smartmontools.sourceforge.net/ === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000b 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0007 165 165 021 Pre-fail Always - 2750 4 Start_Stop_Count 0x0032 100 100 040 Old_age Always - 21 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x000a 200 200 051 Old_age Always - 0 9 Power_On_Hours 0x0032 065 065 000 Old_age Always - 25831 10 Spin_Retry_Count 0x0012 100 253 051 Old_age Always - 0 11 Calibration_Retry_Count 0x0012 100 253 051 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 21 194 Temperature_Celsius 0x0022 116 093 000 Old_age Always - 27 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0012 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0012 200 200 000 Old_age Always - 0 199 UDMA_CRC_Error_Count 0x000a 200 253 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 051 Old_age Offline - 0 # smartctl -A /dev/sdb smartctl version 5.38 [x86_64-redhat-linux-gnu] Copyright (C) 2002-8 Bruce Allen Home page is http://smartmontools.sourceforge.net/ === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0003 180 180 021 Pre-fail Always - 3958 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 22 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x000f 200 200 051 Pre-fail Always - 0 9 Power_On_Hours 0x0032 068 068 000 Old_age Always - 24087 10 Spin_Retry_Count 0x0013 100 253 051 Pre-fail Always - 0 11 Calibration_Retry_Count 0x0013 100 253 051 Pre-fail Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 21 194 Temperature_Celsius 0x0022 122 096 000 Old_age Always - 25 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0012 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0010 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x003e 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0009 200 200 051 Pre-fail Offline - 0 Any idea what's wrong here? Bad motherboard? It would seem rare that both drives are going bad (smartctl says they PASS_, so it leaves the mobo as the culprit in my eyes.