Supermicro P8SC8, CENTOS/RHEL 5.x 2.6.18-128.el5 HD: Seagate SATA ST3120827AS fw3.42 [2 disks in md raid1] 00:1f.1 0101: 8086:266f (rev 03) 00:1f.2 0101: 8086:2652 (rev 03) 2652 is handled by both ata_piix and ahci. Using ata_piix everything is fine, using ahci will cause periodic errors like: ata1.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x6 frozen ata1.00: cmd 61/08:00:4d:6d:c0/00:00:00:00:00/40 tag 0 ncq 4096 out res 40/00:00:b5:95:a7/00:00:00:00:00/40 Emask 0x4 (timeout) ata1.00: status: { DRDY } ata1: hard resetting link ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) ata1.00: configured for UDMA/133 ata1: EH complete SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB) sda: Write Protect is off SCSI device sda: drive cache: write back Using echo 1 > /sys/block/sda/device/queue_depth echo 1 > /sys/block/sdb/device/queue_depth will eliminate the issue, so please add { "ST3120827AS", "3.42", ATA_HORKAGE_NONCQ }, to the NCQ blacklist. Thanks -- giulioo@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html