Inline. On Thu, Dec 30, 2010 at 05:13, Giovanni Tessore <giotex@xxxxxxxxxx> wrote: > On 12/30/2010 04:20 AM, James wrote: >> >> Can someone point me in the right direction? >> (a) what causes these errors precisely? >> (b) is the error benign? How can I determine if it is *likely* a >> hardware problem? (I imagine it's probably impossible to tell if it's >> HW until it's too late) >> (c) are these errors expected in a RAID array that is heavily used? >> (d) what kind of errors should I see regarding "read errors" that >> *would* indicate an imminent hardware failure? > > (a) these errors usually come from defective disk sectors. raid recostructs > the missing sector from parity from other disks in the array, then rewrites > the sector on the defective disk; if the sector is rewritten without error > (maybe the hd remaps the sector into its reserved area), then just the log > messages is displayed. > > (b) with raid-6 it's almost benign; to get troubles you should get a read > error on same sector for >2 disks; or have 2 disks failed and out of the > array and get a read error on one of the other disks while recostructing the > array; or have 1 disk failed and get a read error on same sector on >1 disk > while recostructing (with raid-5 it's almost dangerous instead, as you can > have big troubles if a disk fails and you get a read error on another disk > while recostructing; that happened to me!) > > (c) no; it's also a good rule to perform a periodic scrub of the array > (check of the array), to reveal and correct defective sectors > > (d) check smart status of the disks, for "relocated sectors count"; also if > md superblock is >= 1 there is a persistent count of corrected read errors > for each device into /sys/block/mdXX/md/dev-XX/errors, when this counter > reaches 256 the disk is marked failed; ihmo when a disk is giving even few > corrected read errors in a short interval its better to replace it. Good call. Here's the output of the reallocated sector count: ~ # for i in a b c d ; do smartctl -a /dev/sd$i | grep Realloc ; done 5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 1 5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 3 5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 5 5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 1 Are these values high? Low? Acceptable? How about values like "Raw_Read_Error_Rate" and "Seek_Error_Rate" -- I believe I've read those are values that are normally very high...is this true? ~ # for i in a b c d ; do smartctl -a /dev/sd$i | grep Raw_Read_Error_Rate ; done 1 Raw_Read_Error_Rate 0x000f 116 099 006 Pre-fail Always - 106523474 1 Raw_Read_Error_Rate 0x000f 114 099 006 Pre-fail Always - 77952706 1 Raw_Read_Error_Rate 0x000f 117 099 006 Pre-fail Always - 137525325 1 Raw_Read_Error_Rate 0x000f 118 099 006 Pre-fail Always - 179042738 ...and... ~ # for i in a b c d ; do smartctl -a /dev/sd$i | grep Seek_Error_Rate ; done 7 Seek_Error_Rate 0x000f 072 060 030 Pre-fail Always - 14923821 7 Seek_Error_Rate 0x000f 072 060 030 Pre-fail Always - 15648709 7 Seek_Error_Rate 0x000f 072 060 030 Pre-fail Always - 15733727 7 Seek_Error_Rate 0x000f 071 060 030 Pre-fail Always - 14279452 Thoughts appreciated. > -- > Yours faithfully. > > Giovanni Tessore > > > -- > 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 > -- 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
