Hallo all, I have a very strange behaviour on my RAID-1 array with Kernel 6.6.13. Kernel 6.1.76 and earlier do not show this symptoms, but I *think* I have seen it on any 6.5 Kernel (I am not sure) the array contains my /home, and consists of an internal NVME drive, a internal SATA device, and an external USB drive. even if the array is (neraly) idle, I see very heave I/O on the external USB drive, which makes the system more or less unusable. artus:~ # iostat -p sda,sdb,nvme0n1,md0,md1 -y 5 Linux 6.6.13+bpo-amd64 (artus) 2024-03-17 _x86_64_ (12 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0,12 0,00 0,15 0,45 0,00 99,28 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd md0 2,20 0,00 8,80 0,00 0 44 0 md1 0,00 0,00 0,00 0,00 0 0 0 nvme0n1 8,00 0,00 39,10 0,00 0 195 0 nvme0n1p1 0,00 0,00 0,00 0,00 0 0 0 nvme0n1p2 4,40 0,00 29,60 0,00 0 148 0 nvme0n1p3 3,60 0,00 9,50 0,00 0 47 0 nvme0n1p4 0,00 0,00 0,00 0,00 0 0 0 sda 3,80 0,00 9,50 0,00 0 47 0 sda1 3,80 0,00 9,50 0,00 0 47 0 sda2 0,00 0,00 0,00 0,00 0 0 0 sdb 54,20 0,00 26223,10 0,00 0 131115 0 sdb1 54,20 0,00 26223,10 0,00 0 131115 0 sdb2 0,00 0,00 0,00 0,00 0 0 0 avg-cpu: %user %nice %system %iowait %steal %idle 0,20 0,00 0,12 0,37 0,00 99,32 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd md0 0,20 0,00 0,80 0,00 0 4 0 md1 0,00 0,00 0,00 0,00 0 0 0 nvme0n1 1,60 0,00 3,70 0,00 0 18 0 nvme0n1p1 0,00 0,00 0,00 0,00 0 0 0 nvme0n1p2 0,40 0,00 2,40 0,00 0 12 0 nvme0n1p3 1,20 0,00 1,30 0,00 0 6 0 nvme0n1p4 0,00 0,00 0,00 0,00 0 0 0 sda 1,20 0,00 1,30 0,00 0 6 0 sda1 1,20 0,00 1,30 0,00 0 6 0 sda2 0,00 0,00 0,00 0,00 0 0 0 sdb 39,00 0,00 19661,50 0,00 0 98307 0 sdb1 39,00 0,00 19661,50 0,00 0 98307 0 sdb2 0,00 0,00 0,00 0,00 0 0 0 I am sure that there is no rebuild or check at the moment... and I have no idea WTF is going on here... sometimes the write rate goes up to >100 MB/sec when I check with iotop, i can see similar high write rates, but no process or thread responsible for it. Some more information: artus:~ # uname -a Linux artus 6.6.13+bpo-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.6.13-1~bpo12+1 (2024-02-15) x86_64 GNU/Linux artus:~ # mdadm --version mdadm - v4.2 - 2021-12-30 - Debian 4.2-5 artus:~ # cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md1 : active raid1 sda2[2](W) sdb2[4] 1919826944 blocks super 1.2 [2/2] [UU] bitmap: 0/15 pages [0KB], 65536KB chunk md0 : active raid1 sda1[5](W) nvme0n1p3[3] sdb1[4](W) 33520640 blocks super 1.2 [3/3] [UUU] bitmap: 1/1 pages [4KB], 65536KB chunk unused devices: <none> note: I see similar behaviour on /dev/md1 which is a quite large device containing virtual machines artus:~ # smartctl -H -i -l scterc /dev/sda smartctl 7.3 2022-02-28 r5338 [x86_64-linux-6.6.13+bpo-amd64] (local build) Copyright (C) 2002-22, Bruce Allen, Christian Franke, www.smartmontools.org === START OF INFORMATION SECTION === Model Family: Samsung based SSDs Device Model: Samsung SSD 870 EVO 2TB Serial Number: S6P4NF0W307661D LU WWN Device Id: 5 002538 f43329aaa Firmware Version: SVT02B6Q User Capacity: 2.000.398.934.016 bytes [2,00 TB] Sector Size: 512 bytes logical/physical Rotation Rate: Solid State Device Form Factor: 2.5 inches TRIM Command: Available, deterministic, zeroed Device is: In smartctl database 7.3/5319 ATA Version is: ACS-4 T13/BSR INCITS 529 revision 5 SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s) Local Time is: Sun Mar 17 11:06:23 2024 CET SMART support is: Available - device has SMART capability. SMART support is: Enabled === START OF READ SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED SCT Error Recovery Control: Read: Disabled Write: Disabled artus:~ # smartctl -d sat,auto -H -i -l scterc /dev/sdb smartctl 7.3 2022-02-28 r5338 [x86_64-linux-6.6.13+bpo-amd64] (local build) Copyright (C) 2002-22, Bruce Allen, Christian Franke, www.smartmontools.org === START OF INFORMATION SECTION === Vendor: Samsung Product: PSSD T7 Revision: 0 Compliance: SPC-4 User Capacity: 2.000.398.934.016 bytes [2,00 TB] Logical block size: 512 bytes LU is fully provisioned Rotation Rate: Solid State Device Logical Unit id: 0x5000000000000001 Serial number: K611523T0SNDT5S Device type: disk Local Time is: Sun Mar 17 11:13:59 2024 CET SMART support is: Available - device has SMART capability. SMART support is: Enabled Temperature Warning: Disabled or Not Supported === START OF READ SMART DATA SECTION === SMART Health Status: OK artus:~ # smartctl -H -i -l scterc /dev/nvme0n1 smartctl 7.3 2022-02-28 r5338 [x86_64-linux-6.6.13+bpo-amd64] (local build) Copyright (C) 2002-22, Bruce Allen, Christian Franke, www.smartmontools.org === START OF INFORMATION SECTION === Model Number: TS512GMTE400S Serial Number: I216681028 Firmware Version: V0804S3 PCI Vendor/Subsystem ID: 0x1d79 IEEE OUI Identifier: 0x7c3548 Controller ID: 1 NVMe Version: 1.3 Number of Namespaces: 1 Namespace 1 Size/Capacity: 512.110.190.592 [512 GB] Namespace 1 Formatted LBA Size: 512 Namespace 1 IEEE EUI-64: 7c3548 52255b6444 Local Time is: Sun Mar 17 11:08:56 2024 CET === START OF SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED artus:~ # mdadm --examine /dev/sda1 /dev/sda1: Magic : a92b4efc Version : 1.2 Feature Map : 0x1 Array UUID : f6189e48:e5dadfbd:8a7a9239:c6074410 Name : any:home Creation Time : Fri Nov 15 07:07:21 2019 Raid Level : raid1 Raid Devices : 3 Avail Dev Size : 67041280 sectors (31.97 GiB 34.33 GB) Array Size : 33520640 KiB (31.97 GiB 34.33 GB) Data Offset : 67584 sectors Super Offset : 8 sectors Unused Space : before=67504 sectors, after=0 sectors State : clean Device UUID : 9023e389:b12c69be:abd226c2:fceba209 Internal Bitmap : 8 sectors from superblock Flags : write-mostly Update Time : Sun Mar 17 11:15:22 2024 Bad Block Log : 512 entries available at offset 16 sectors Checksum : 7958e05b - correct Events : 864895 Device Role : Active device 2 Array State : AAA ('A' == active, '.' == missing, 'R' == replacing) artus:~ # mdadm --examine /dev/sdb1 /dev/sdb1: Magic : a92b4efc Version : 1.2 Feature Map : 0x1 Array UUID : f6189e48:e5dadfbd:8a7a9239:c6074410 Name : any:home Creation Time : Fri Nov 15 07:07:21 2019 Raid Level : raid1 Raid Devices : 3 Avail Dev Size : 67041280 sectors (31.97 GiB 34.33 GB) Array Size : 33520640 KiB (31.97 GiB 34.33 GB) Data Offset : 67584 sectors Super Offset : 8 sectors Unused Space : before=67504 sectors, after=0 sectors State : clean Device UUID : a5a29aca:ebfaa7b1:c484660d:bb455305 Internal Bitmap : 8 sectors from superblock Flags : write-mostly Update Time : Sun Mar 17 11:15:34 2024 Bad Block Log : 512 entries available at offset 16 sectors Checksum : f43f398c - correct Events : 864895 Device Role : Active device 1 Array State : AAA ('A' == active, '.' == missing, 'R' == replacing) artus:~ # mdadm --examine /dev/nvme0n1p3 /dev/nvme0n1p3: Magic : a92b4efc Version : 1.2 Feature Map : 0x1 Array UUID : f6189e48:e5dadfbd:8a7a9239:c6074410 Name : any:home Creation Time : Fri Nov 15 07:07:21 2019 Raid Level : raid1 Raid Devices : 3 Avail Dev Size : 67041280 sectors (31.97 GiB 34.33 GB) Array Size : 33520640 KiB (31.97 GiB 34.33 GB) Data Offset : 67584 sectors Super Offset : 8 sectors Unused Space : before=67504 sectors, after=0 sectors State : clean Device UUID : dae5b41c:8eaceaae:d65a1486:819723c1 Internal Bitmap : 8 sectors from superblock Update Time : Sun Mar 17 11:16:38 2024 Bad Block Log : 512 entries available at offset 16 sectors Checksum : 781a567b - correct Events : 864895 Device Role : Active device 0 Array State : AAA ('A' == active, '.' == missing, 'R' == replacing) artus:~ # mdadm --detail /dev/md0 /dev/md0: Version : 1.2 Creation Time : Fri Nov 15 07:07:21 2019 Raid Level : raid1 Array Size : 33520640 (31.97 GiB 34.33 GB) Used Dev Size : 33520640 (31.97 GiB 34.33 GB) Raid Devices : 3 Total Devices : 3 Persistence : Superblock is persistent Intent Bitmap : Internal Update Time : Sun Mar 17 11:19:35 2024 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 0 Spare Devices : 0 Consistency Policy : bitmap Name : any:home UUID : f6189e48:e5dadfbd:8a7a9239:c6074410 Events : 864895 Number Major Minor RaidDevice State 3 259 3 0 active sync /dev/nvme0n1p3 4 8 17 1 active sync writemostly /dev/sdb1 5 8 1 2 active sync writemostly /dev/sda1 Any hints? If you need more information, please let me know. sunny greetings from Austria, Michael -- Michael Reinelt <michael@xxxxxxxxxxxxx> Ringsiedlung 75 A-8111 Gratwein-Straßengel +43 676 3079941