Re: Raid0 rebuild slows to a crawl

[Kay Diederichs <kay.diederichs@uni-konstanz.de>]

On 01/13/2012 09:01 AM, David Liontooth wrote:
>
> I'm trying to use a WD3200AAKX-001CA0 drive in a raid1 configuration
> (Debian squeeze mdadm 3.1.4-1+8efb9d1), but adding it is unusably slow:
>
> # cat /proc/mdstat
> Personalities : [raid1]
> md1 : active raid1 sdb3[2] sda3[1]
> 73015360 blocks [2/1] [_U]
> [>....................] recovery = 0.0% (28928/73015360)
> finish=2521.6min speed=482K/sec
>
> dmesg shows no errors:
>
> md: recovery of RAID array md0
> md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
> md: using maximum available idle IO bandwidth (but not more than 200000
> KB/sec) for recovery.
>
> The drive itself doesn't seem to have a problem, though it's not
> particularly fast:
>
> # hdparm -tT /dev/sdb
>
> /dev/sdb:
> Timing cached reads: 11220 MB in 2.00 seconds = 5614.03 MB/sec
> Timing buffered disk reads: 174 MB in 6.44 seconds = 27.01 MB/sec
>
> # smartctl -a /dev/sdb
>
> 5 Reallocated_Sector_Ct 0x0033 133 133 140 Pre-fail Always FAILING_NOW 1265
>
> # hdparm -i /dev/sdb
>
> /dev/sdb:
>
> Model=WDC WD3200AAKX-001CA0, FwRev=15.01H15, SerialNo=WD-WCAYUEJ66523
> Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
> RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50
> BuffType=unknown, BuffSize=16384kB, MaxMultSect=16, MultSect=off
> CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=625142448
> IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
> PIO modes: pio0 pio3 pio4
> DMA modes: mdma0 mdma1 mdma2
> UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6
> AdvancedPM=no WriteCache=enabled
> Drive conforms to: Unspecified: ATA/ATAPI-1,2,3,4,5,6,7
>
> * signifies the current active mode
>
> Is this a known problem? Only see it with this WD drive.
>
> Cheers,
> Dave
>
>
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Hi Dave,

I'd say your drive is dying if its Reallocated_Sector_Ct is 1265. Dying 
drives often are really slow; they spend the time on trying to overcome 
error states.

HTH,
Kay