On Wed, Apr 21, 2010 at 8:14 AM, Phillip Susi <psusi@xxxxxxxxxx> wrote: <SNIP> > I've not seen any anecdotal stories, but I have seen plenty of reports > with real data showing a large number of head unloads from the SMART > data after a relatively short period of use. Personally mine has a few > hundred so far and I have not even used it for real storage yet, only > testing. The specifications say it's good for 300,000 cycles, so do the > math... getting 5 unloads per minute would lead to probable failure > after 41 days. Granted that is about worst case, but still something to > watch out for. In order to make it the entire 3 year warranty period, > you need to stay under 11.4 unloads per hour. If you have very little > IO activity, or VERY MUCH, then this is entirely possible, but more > moderate loads in the middle have been observed to cause hundreds of > unloads per hour. > > Given that, and the fact that WD themselves have stated that you should > not use these drives in a raid array, I'd either stay away, or watch out > for this problem and try to take action to avoid and monitor it. I think I reported this earlier, but here is a WD10EARS drive in a standard Gentoo Linux desktop machine. The drive has 1661 hours powered up and 43508 load cycles. That's 26/hour and works out to about 14 months before it will be out of spec at 300K cycles. This machine only gets a few hours of use a day but is generally powered up all the time. I don't know why Linux wakes this drive up roughly every two minutes, assuming it's Linux and not the drive itself or something on the motherboard, but it does. I tried three of these drives in a RAID1 in another machine and they simply didn't work. Went off line over and over, with big wait times when they were working. I made no other changes expect changing to a WD 500GB RAID Edition drive and get almostno load cycle counts at all. - Mark gandalf ~ # smartctl -i /dev/sda smartctl 5.39.1 2010-01-28 r3054 [x86_64-pc-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net === START OF INFORMATION SECTION === Device Model: WDC WD10EARS-00Y5B1 Serial Number: WD-WCAV55464493 Firmware Version: 80.00A80 User Capacity: 1,000,204,886,016 bytes Device is: Not in smartctl database [for details use: -P showall] ATA Version is: 8 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Wed Apr 21 10:35:32 2010 PDT SMART support is: Available - device has SMART capability. SMART support is: Enabled gandalf ~ # gandalf ~ # smartctl -A /dev/sda smartctl 5.39.1 2010-01-28 r3054 [x86_64-pc-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, 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 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 129 128 021 Pre-fail Always - 6525 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 21 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0 9 Power_On_Hours 0x0032 098 098 000 Old_age Always - 1661 10 Spin_Retry_Count 0x0032 100 253 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 253 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 20 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 5 193 Load_Cycle_Count 0x0032 186 186 000 Old_age Always - 43508 194 Temperature_Celsius 0x0022 121 116 000 Old_age Always - 26 196 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 - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 gandalf ~ # -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
