Messages in this thread | | | From | Grant Coady <> | Subject | Problem with shared interrupt latency with a RAID6 array? | Date | Wed, 22 Dec 2010 22:57:57 +1100 |
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Hi there,
Built my first RAID6 array with 5 x 1TB SATA drives.
I notice this odd number in the SMART values for the last two drives on the array. The drives connect to an Intel ICH9R chip, the mobo has a 2.13GHz Core2Duo CPU and 4GB memory, running Slackware64-13.1 with 2.6.36.2a kernel.
While feeding data into the array from a USB 2.0 attached drive, the box's load average was about 3.5, the box was very responsive and I transferred over 900GB into the RAID6 array.
The fourth and fifth drives report lots of command timeouts in the SMART data. Is this a problem?
Is it because the drives share an interrupt?
Extract from dmesg:
root@pooh:~# egrep -e '^(ahci|ata)' /var/log/dmesg ahci 0000:00:1f.2: version 3.0 ahci 0000:00:1f.2: PCI INT B -> GSI 19 (level, low) -> IRQ 19 ahci 0000:00:1f.2: irq 40 for MSI/MSI-X ahci: SSS flag set, parallel bus scan disabled ahci 0000:00:1f.2: AHCI 0001.0200 32 slots 6 ports 3 Gbps 0x3f impl SATA mode ahci 0000:00:1f.2: flags: 64bit ncq sntf stag pm led clo pmp pio slum part ccc ems ahci 0000:00:1f.2: setting latency timer to 64 ata1: SATA max UDMA/133 abar m2048@0xf6386000 port 0xf6386100 irq 40 ata2: SATA max UDMA/133 abar m2048@0xf6386000 port 0xf6386180 irq 40 ata3: SATA max UDMA/133 abar m2048@0xf6386000 port 0xf6386200 irq 40 ata4: SATA max UDMA/133 abar m2048@0xf6386000 port 0xf6386280 irq 40 ata5: SATA max UDMA/133 abar m2048@0xf6386000 port 0xf6386300 irq 40 ata6: SATA max UDMA/133 abar m2048@0xf6386000 port 0xf6386380 irq 40 ata7: PATA max UDMA/100 cmd 0xc000 ctl 0xc100 bmdma 0xc400 irq 16 ata8: PATA max UDMA/100 cmd 0xc200 ctl 0xc300 bmdma 0xc408 irq 16 ata7.00: ATAPI: PIONEER DVD-RW DVR-110D, 1.41, max UDMA/66 ata7.00: configured for UDMA/66 ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata1.00: ATA-8: ST31000528AS, CC46, max UDMA/133 ata1.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 31/32) ata1.00: configured for UDMA/133 ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata2.00: ATA-8: ST31000528AS, CC46, max UDMA/133 ata2.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 31/32) ata2.00: configured for UDMA/133 ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata3.00: ATA-8: ST31000528AS, CC46, max UDMA/133 ata3.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 31/32) ata3.00: configured for UDMA/133 ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata4.00: ATA-8: ST31000528AS, CC46, max UDMA/133 ata4.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 31/32) ata4.00: configured for UDMA/133 ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata5.00: ATA-8: ST31000528AS, CC46, max UDMA/133 ata5.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 31/32) ata5.00: configured for UDMA/133 ata6: SATA link down (SStatus 0 SControl 300)
And here's SMART's command timeout numbers:
root@pooh:~# for d in a b c d e; do smartctl -a /dev/sd${d} |grep Command_Timeout; done 188 Command_Timeout 0x0032 100 100 000 Old_age Always - 0 188 Command_Timeout 0x0032 100 100 000 Old_age Always - 0 188 Command_Timeout 0x0032 100 100 000 Old_age Always - 0 188 Command_Timeout 0x0032 100 100 000 Old_age Always - 65537 188 Command_Timeout 0x0032 100 100 000 Old_age Always - 65537
Is this a problem? Is there something I can change in the .config?
Config and full dmesg are at:
http://bugsplatter.id.au/kernel/boxen/pooh/config-2.6.36.2a.gz http://bugsplatter.id.au/kernel/boxen/pooh/dmesg-2.6.36.2a.gz
Ask, and I'll provide more info, do tests and so on.
Could this issue be related to RAID6 unreliability reports one finds for some Linux based NAS devices on the 'net?
Thanks, Grant.
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