When working with our Debian 7 production server (kernel 3.2.0-4-amd64) on Supermicro X10SLL-F hardware, we consistently encounter SATA link reset errors across all connected drives (2 SSDs and 2 HDDs). The kernel messages show:

ata1: exception Emask 0x50 SAct 0x0 SErr 0x4090800 action 0xe frozen
ata1: irq_stat 0x00400040, connection status changed
ata1: SError: { HostInt PHYRdyChg 10B8B DevExch }
ata1: hard resetting link

After reviewing multiple bug reports, we implemented several common fixes:

1. Disabling NCQ:

for dev in /sys/block/sd[a-d]; do
    echo 1 > $dev/device/queue_depth
done

2. Adjusting power management:

echo "medium_power" > /sys/class/scsi_host/host0/link_power_management_policy

The SATA link speed degrades from 6.0Gbps to 1.5Gbps after errors occur. Checking the controller details:

lspci -nn | grep SATA
00:1f.2 SATA controller [0106]: Intel Corporation Lynx Point 6-port SATA Controller 1 [AHCI mode] [8086:8c02] (rev 04)

1. Kernel Parameters:
Try adding these to GRUB configuration:

libata.force=noncq
libata.force=1.5Gbps
ahci.no_em_buffer=1

2. Firmware Updates:
Check for BIOS updates from Supermicro and firmware updates for both SSDs (Toshiba) and HDDs (Seagate).

3. Physical Connections:
Despite affecting all drives simultaneously, worth checking:

for i in {1..6}; do
    echo "Link $i:" $(cat /sys/class/ata_link/link$i/sata_spd)
done

Create a monitoring script to log link resets:

#!/bin/bash
LOG=/var/log/sata_resets.log
dmesg -w | grep --line-buffered "hard resetting link" | \
while read line; do
    echo "$(date) - $line" >> $LOG
done

Enable detailed ATA debugging:

echo 1 > /sys/module/libata/parameters/debug
dmesg -wH

This will show detailed state transitions and may reveal timing issues during link negotiation.

---

When dealing with SATA link errors on Linux systems with Intel Lynx Point controllers, the kernel typically logs messages like this:

ata1: exception Emask 0x50 SAct 0x0 SErr 0x4090800 action 0xe frozen
ata1: irq_stat 0x00400040, connection status changed
ata1: SError: { HostInt PHYRdyChg 10B8B DevExch }
ata1: hard resetting link

This issue frequently appears in production environments with:

• Supermicro X10 series motherboards
• Intel Lynx Point SATA controllers (AHCI mode)
• Mixed SSD/HDD configurations
• Debian/Ubuntu systems with kernel versions 3.x-5.x

From my troubleshooting experience, these are the most likely culprits:

# Check current link speed (example for /dev/sda)
cat /sys/class/ata_link/link1/sata_spd

# Verify controller capabilities
lspci -vvv -s $(lspci | grep SATA | cut -d' ' -f1)

Step 1: Verify Physical Connections

Before diving into software solutions:

1. Reseat all SATA cables
2. Try different SATA ports
3. Check power supply connections

Step 2: Adjust Kernel Parameters

Try these tweaks in /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="... libata.force=noncq libata.force=1.5Gbps pcie_aspm=off"

Then update GRUB and reboot:

update-grub && reboot

Step 3: Power Management Settings

For each host controller (adjust hostX as needed):

for host in /sys/class/scsi_host/host*; do
  echo "min_power" > ${host}/link_power_management_policy
done

When basic fixes don't work, try these:

# Enable detailed ATA debugging
echo 1 > /sys/kernel/debug/tracing/events/ata/enable
cat /sys/kernel/debug/tracing/trace_pipe

# Check for controller-specific quirks
modinfo ahci | grep flags

Consider these last-resort options:

• Upgrade to a newer kernel (4.19+ has improved Lynx Point support)
• Disable ASPM completely in BIOS
• Try a different SATA controller mode (RAID instead of AHCI)
• Replace the SATA controller with an LSI HBA

Create a simple monitoring script:

#!/bin/bash
LOG=/var/log/sata_errors.log
dmesg | grep -E "exception Emask|hard resetting link" >> $LOG
if [ -s $LOG ]; then
  mail -s "SATA Errors Detected" admin@example.com < $LOG
fi