The spin-down seems to be the issue here.
The array run for 2 weeks now with spin-down set to never.
I started yesterday with setting individual disks to spin-down after 15mins.
Almost all of my disks work with this.
Only my Exos X18 (Disk11 /dev/sdk) disks don't.
Nov 16 10:19:32 Alpha-Unraid kernel: mdcmd (74): set md_num_stripes 1280
Nov 16 10:19:32 Alpha-Unraid kernel: mdcmd (75): set md_queue_limit 80
Nov 16 10:19:32 Alpha-Unraid kernel: mdcmd (76): set md_sync_limit 5
Nov 16 10:19:32 Alpha-Unraid kernel: mdcmd (77): set md_write_method
Nov 16 10:19:32 Alpha-Unraid emhttpd: spinning down /dev/sdk
Nov 16 10:20:01 Alpha-Unraid flash_backup: adding task: /usr/local/emhttp/plugins/dynamix.my.servers/scripts/UpdateFlashBackup update
Nov 16 10:20:47 Alpha-Unraid kernel: sd 11:0:5:0: attempting task abort!scmd(0x000000000658e7e8), outstanding for 7050 ms & timeout 7000 ms
Nov 16 10:20:47 Alpha-Unraid kernel: sd 11:0:5:0: [sdk] tag#6626 CDB: opcode=0x85 85 06 20 00 d8 00 00 00 00 00 4f 00 c2 00 b0 00
Nov 16 10:20:47 Alpha-Unraid kernel: scsi target11:0:5: handle(0x000e), sas_address(0x5001517e3b0bf0aa), phy(10)
Nov 16 10:20:47 Alpha-Unraid kernel: scsi target11:0:5: enclosure logical id(0x5001e677b6dbbfff), slot(10)
Nov 16 10:20:47 Alpha-Unraid kernel: sd 11:0:5:0: device_block, handle(0x000e)
Nov 16 10:20:49 Alpha-Unraid kernel: sd 11:0:5:0: device_unblock and setting to running, handle(0x000e)
Nov 16 10:20:50 Alpha-Unraid kernel: sd 11:0:5:0: task abort: SUCCESS scmd(0x000000000658e7e8)
Nov 16 10:20:50 Alpha-Unraid kernel: sd 11:0:5:0: [sdk] Synchronizing SCSI cache
Nov 16 10:20:50 Alpha-Unraid kernel: sd 11:0:5:0: [sdk] Synchronize Cache(10) failed: Result: hostbyte=0x01 driverbyte=DRIVER_OK
Nov 16 10:20:50 Alpha-Unraid kernel: mpt2sas_cm0: mpt3sas_transport_port_remove: removed: sas_addr(0x5001517e3b0bf0aa)
Nov 16 10:20:50 Alpha-Unraid kernel: mpt2sas_cm0: removing handle(0x000e), sas_addr(0x5001517e3b0bf0aa)
Nov 16 10:20:50 Alpha-Unraid kernel: mpt2sas_cm0: enclosure logical id(0x5001e677b6dbbfff), slot(10)
Nov 16 10:20:50 Alpha-Unraid emhttpd: read SMART /dev/sdk
Nov 16 10:20:50 Alpha-Unraid kernel: mpt2sas_cm0: handle(0xe) sas_address(0x5001517e3b0bf0aa) port_type(0x1)
Nov 16 10:20:51 Alpha-Unraid kernel: scsi 11:0:15:0: Direct-Access ATA ST16000NM000J-2T SC02 PQ: 0 ANSI: 6
Nov 16 10:20:51 Alpha-Unraid kernel: scsi 11:0:15:0: SATA: handle(0x000e), sas_addr(0x5001517e3b0bf0aa), phy(10), device_name(0x0000000000000000)
Nov 16 10:20:51 Alpha-Unraid kernel: scsi 11:0:15:0: enclosure logical id (0x5001e677b6dbbfff), slot(10)
Nov 16 10:20:51 Alpha-Unraid kernel: scsi 11:0:15:0: atapi(n), ncq(y), asyn_notify(n), smart(y), fua(y), sw_preserve(y)
Nov 16 10:20:51 Alpha-Unraid kernel: scsi 11:0:15:0: qdepth(32), tagged(1), scsi_level(7), cmd_que(1)
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: Attached scsi generic sg10 type 0
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: Power-on or device reset occurred
Nov 16 10:20:51 Alpha-Unraid kernel: end_device-11:0:11: add: handle(0x000e), sas_addr(0x5001517e3b0bf0aa)
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: [sdt] 31251759104 512-byte logical blocks: (16.0 TB/14.6 TiB)
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: [sdt] 4096-byte physical blocks
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: [sdt] Write Protect is off
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: [sdt] Mode Sense: 7f 00 10 08
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: [sdt] Write cache: enabled, read cache: enabled, supports DPO and FUA
Nov 16 10:20:51 Alpha-Unraid kernel: sdt: sdt1
Nov 16 10:20:51 Alpha-Unraid kernel: sd 11:0:15:0: [sdt] Attached SCSI disk
Nov 16 10:20:52 Alpha-Unraid unassigned.devices: Disk with ID 'ST16000NM000J-2TW103_ZR5AGC4V ()' is not set to auto mount.
Nov 16 10:20:53 Alpha-Unraid emhttpd: error: hotplug_devices, 1706: No such file or directory (2): tagged device ST16000NM000J-2TW103_ZR5AGC4V was (sdk) is now (sdt)
Nov 16 10:20:53 Alpha-Unraid emhttpd: read SMART /dev/sdt
Nov 16 10:20:53 Alpha-Unraid kernel: emhttpd[10420]: segfault at 67c ip 000056528418775f sp 00007ffd34b8b620 error 4 in emhttpd[565284172000+24000] likely on CPU 8 (core 10, socket 0)
Nov 16 10:20:53 Alpha-Unraid kernel: Code: c4 36 01 00 48 89 45 f8 48 8d 05 f9 23 01 00 48 89 45 f0 e9 79 01 00 00 8b 45 ec 89 c7 e8 1a 88 ff ff 48 89 45 d8 48 8b 45 d8 <8b> 80 7c 06 00 00 85 c0 0f 94 c0 0f b6 c0 89 45 d4 48 8b 45 e0 48
Nov 16 10:21:01 Alpha-Unraid flash_backup: adding task: /usr/local/emhttp/plugins/dynamix.my.servers/scripts/UpdateFlashBackup update