You might assume you have a bad drive or the SATA interface/cable is bad, or the power supply is bad/weak to the drive. These are all possible issues, but definitely check your SATA cable for "twisting". It is a big issue because until the error stops or times out, your system will not boot (in my case this was the case even though the drive with the issue was not part of the OS or booting process at all).
If you run an open rig that you move around often that ha........
This is the closest way to disabling it without using the "libata.force=noncq" kernel boot option is to set the queue to a depth of 1 which doesn't actually disable it.
Change the sdc below to match the device you want to disable NCQ for.
[root@officebox ~]# echo "1" > /sys/block/sdc/device/queue_depth
Errors that indicate you are having a performance issue are these in messages or dmesg relating to N........
[ 2868.041375] ata1: EH in SWNCQ mode,QC:qc_active 0x40 sactive 0x40
[ 2868.041554] ata1: SWNCQ:qc_active 0x40 defer_bits 0x0 last_issue_tag 0x6
[ 2868.041556] dhfis 0x40 dmafis 0x40 sdbfis 0x20
[ 2868.041874] ata1: ATA_REG 0x41 ERR_REG 0x84
[ 2868.042013] ata1: tag : dhfis dmafis sdbfis sactive
[ 2868.042163] ata1: tag 0x6: 1 1 0 1
[ 2868.042301] ata1.00: exception Emask 0x1 SAct 0x40 SErr 0x400000 action 0x6 frozen
[........
Another new drive bad from the start:
Jun 2 15:14:18 one-desktop kernel: [15895.386779] ata2.00: exception Emask 0x50 SAct 0x1 SErr 0x280900 action 0x6 frozen
Jun 2 15:14:18 one-desktop kernel: [15895.386782] ata2.00: irq_stat 0x08000000, interface fatal error
Jun 2 15:14:18 one-desktop kernel: [15895.386784] ata2: SError: { UnrecovData HostInt 10B8B BadCRC }
Jun 2 15:14:18 one-desktop kernel: [15895.386788] ata2.00: cmd 60/0........
This is just trying to read 5GB off the drive with dd and the drive initially tested ok but shortly after I wondered why I was seeing 2MB/s read speeds. Notice the "current_pending_sector", anytime I've seen it at anything above 0 even with no other bad fields/attributes, it means the drive is bad.
ata1.00: exception Emask 0x0 SAct 0x3 SErr 0x0 action 0x0
ata1.00: irq_stat 0x40000008
ata1.00: failed command: READ FPDMA QUEUED
ata1.00: cmd 60/00:00:........
I like dd, although it only reads it, usually a read test of the entire disk will uncover if your hard drive is bad in some parts. This is a good thing to do at least once a month, a lot of times bizarre program behavior, laginess and crashing/unnmounting problems etc.. are due to a failing disc and SMART won't know it or indicate a problem:
We must also remember there's never a guarantee, I've found that ever since we moved to larger and more platters per drive with 1TB drives........
This happened during a RAID array check:
SMART says both drives pass the test, but I'm doing a long test on them and hopefully this is not a hardware error.
Apr 3 04:22:01 remote kernel: md: syncing RAID array md2
Apr 3 04:22:01 remote kernel: md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc.
Apr 3 04:22:01 remote kernel: md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reconstruction.
Apr........
[137392.910057] ata4.00: exception Emask 0x0 SAct 0x1 SErr 0x80000 action 0x6 frozen
[137392.910077] ata4: SError: { 10B8B }
[137392.910095] ata4.00: cmd 60/20:00:00:00:00/00:00:00:00:00/40 tag 0 ncq 16384 in
[137392.910099] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[137392.910122] ata4.00: status: { DRDY }
[137392.910135] ata4: hard resetting link
[137393.440060] ata4: SATA link........
[27969.398749] sd 5:0:0:0: [sdb] 3907029168 512-byte hardware sectors (2000399 MB)
[27969.398749] sd 5:0:0:0: [sdb] Write Protect is off
[27969.398749] sd 5:0:0:0: [sdb] Mode Sense: 00 3a 00 00
[27969.398749] sd 5:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[27972.117543] ata6.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x0
[27972.117543] ata6.00: irq_stat 0x48000000
[27972.117543] ata6.00: cmd 60/08:00:ff:7........
This drive is clearly on the way out, the Kernel knows it but I'm surprised that SMART is not concerned. I didn't blame Seagate for their past issues until now. This hard drive has hardly been used and has not even been powered on for a year according to SMART.
Home page is http://smartmontools.sourceforge.net/
=== START OF INFORMATION SECTION ===
Model Family: Seagate Barracuda 7200.11
Device........