Hi, >> I'm not sure what stats I could provide to troubleshoot this further. >> At this rate, the 2.7T array will take a full day to resync. Is that >> to be expected? > > 1) did you try increasing stripe_cache_size? > > 2) maybe it's an "Advanced Format" drive, the RAID partition is not properly > aligned? I'm not familiar with either of those settings. The sync speed is now down to about 6M/sec, or about two days. I tried increasing the stripe_cache_size with various values, including 1024, 4096, and 8192 from the default 256. Looks like the 1024 is the best, but with only a marginal increase in speed from the 256. It's now about 8M/sec. What is an AF drive? According to dstat, after watching for a few minutes, there are some large reads (15-17M), but all writes are small, and there are times when read and write are very low or near zero. There are four disks in the system. One is a WD and the others are Seagate's of the same model. Does this tell you anything? # hdparm -i /dev/sda /dev/sda: Model=WDC WD1002FAEX-00Z3A0, FwRev=05.01D05, SerialNo=WD-WMATR0921907 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50 BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=1953525168 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 # hdparm -i /dev/sdb /dev/sdb: Model=ST31000340NS, FwRev=SN06, SerialNo=9QJ70X3C Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4 BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=1953525168 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=no WriteCache=enabled Drive conforms to: unknown: ATA/ATAPI-4,5,6,7 Any ideas greatly appreciated. The system is also now horribly slow. Thanks, Alex -- 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