RN312 random volume degraded with no indication why

---

Regis-IT wrote:

Many thanks StephenB, PM sent.

---

dmesg.log (among others) is flooded with unrecoverable read errors on disk 1 (sda, serial # WD-WCC4N7VXZF16)

[Mon Jul  8 11:07:43 2024] do_marvell_9170_recover: ignoring PCI device (8086:3a22) at PCI#0
[Mon Jul  8 11:07:43 2024] ata1.00: exception Emask 0x0 SAct 0x4000 SErr 0x0 action 0x0
[Mon Jul  8 11:07:43 2024] ata1.00: irq_stat 0x40000008
[Mon Jul  8 11:07:43 2024] ata1.00: failed command: READ FPDMA QUEUED
[Mon Jul  8 11:07:43 2024] ata1.00: cmd 60/01:70:4f:00:90/00:00:00:00:00/40 tag 14 ncq 512 in
         res 41/40:00:4f:00:90/00:00:00:00:00/40 Emask 0x409 (media error)
[Mon Jul  8 11:07:43 2024] ata1.00: status: { DRDY ERR }
[Mon Jul  8 11:07:43 2024] ata1.00: error: { UNC }
[Mon Jul  8 11:07:43 2024] ata1.00: configured for UDMA/133
[Mon Jul  8 11:07:43 2024] sd 0:0:0:0: [sda] tag#14 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[Mon Jul  8 11:07:43 2024] sd 0:0:0:0: [sda] tag#14 Sense Key : Medium Error [current] [descriptor] 
[Mon Jul  8 11:07:43 2024] sd 0:0:0:0: [sda] tag#14 Add. Sense: Unrecovered read error - auto reallocate failed
[Mon Jul  8 11:07:43 2024] sd 0:0:0:0: [sda] tag#14 CDB: Read(16) 88 00 00 00 00 00 00 90 00 4f 00 00 00 01 00 00
[Mon Jul  8 11:07:43 2024] blk_update_request: I/O error, dev sda, sector 9437263

 So you need to replace this disk.

WD no longer makes WD30EFRX.  If you want to stick with WD 3 TB, then good options are the WD30EFPX or WD30EFZX (WD Red Plus drives that replace the WD30EFRX).  Avoid the WD Red version (WD30EFAX) as this is SMR, and not a good option for RAID.

There's no problem with mixing WD and Seagate in the same array so you can also get the Seagate Ironwolf (ST3000VN006). 

If you get a larger drive, you won't get additional space until you replace sdb with one of the same size.

Netgear recommends making sure you have an up-to-date backup before manipulating disks, and I agree.  At the moment your array is unprotected, and that will continue until the problem drive is replaced and synced to drive 2.