Hello, I'm new to this list and I signed up, because I found an instability with the following sata controller: Product name: Delock 89384 10 Port PCIe 2.0 x2 Low Profile retail Identifies as: 03:00.0 SATA controller: ASMedia Technology Inc. Device 0625 (rev 01) (PCIe to 10x sata controller card) Problem description: The controller works and recognizes all my drives. But under heavy load, e. g. a mdadm raid-6 resync or just a dd to a file, it keeps causing lockups and random device link resettings on multiple devices. I spend the last two weeks on replacing components in this server, the controller is definitely the problem. Everything works fine with a Marvell 9215 controller and I tried the controller with three different mainboards and kernel versions 3.2, 4.4 and 4.10. The controller or its kernel driver definitely cause these lock ups. I made sure, that all drives were properly connected. [Syslog attached at the bottom of this mail.] As I am an experienced linux user, but new to this, first questions: Is this the right place to seek for help? If not so: Where might I get help with this? If so: Does anybody have an idea, what might causes this problem. My abilities: I can test patches on the mainline kernel. I can't code, as I lack any kind of knowledge about the sata standard. I have the controller card and an empty spare device here, to run any kind of tests. Syslog of one of these resets: If the level of stress is high enough, they happen on all connected devices (seemingly random) from different manufacturers (WesternDigital and Seagate) and different types of models. So this is probably not a bug in the firmware of one of the drives. Log: Mar 24 09:01:43 Server1 kernel: [ 1807.338347] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen Mar 24 09:01:43 Server1 kernel: [ 1807.340701] ata3.00: failed command: FLUSH CACHE EXT Mar 24 09:01:43 Server1 kernel: [ 1807.343078] ata3.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 Mar 24 09:01:43 Server1 kernel: [ 1807.343078] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout) Mar 24 09:01:43 Server1 kernel: [ 1807.349717] ata3.00: status: { DRDY } Mar 24 09:01:43 Server1 kernel: [ 1807.353029] ata3: hard resetting link Mar 24 09:01:43 Server1 kernel: [ 1807.665533] ata3: SATA link up 6.0 Gbps (SStatus 133 SControl 300) Mar 24 09:01:43 Server1 kernel: [ 1807.667000] ata3.00: configured for UDMA/133 Mar 24 09:01:43 Server1 kernel: [ 1807.667007] ata3.00: retrying FLUSH 0xea Emask 0x4 Mar 24 09:01:43 Server1 kernel: [ 1807.667164] ata3.00: device reported invalid CHS sector 0 Mar 24 09:01:43 Server1 kernel: [ 1807.667183] ata3: EH complete Whenever such a lock up happens, the whole partition is not read or writeable for at least 90 seconds and sometimes several minutes. But the system never crashed. I tried to google the controller card, didn't find much about it. Any advice would be much appreciated :). Greetings, Matthias