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I am using my RN104 as a backup device sonce a very, very long time w/o any issues... Cool thing, not high performance, but good it works :-).
I changed in my RN104 one of the 4 harddrives. Before I had 4x 4TB WD red harddrives. I exchanged a old one some days/weeks ago (regular exchange without failiure). Now I have the following setup:
1x WD80EFBX; 2x WD60EFAX; 1x WD60EFRX
The front display shows "DEGRADED" error message - same on the web frontend, but no progress.
"green" traffic light on all 4 devices
mdadm --detail /dev/md127 shows "degraded", but I do not know why and I have no idea how that happend (is ithis normal) or any idea how to fix that?
md127 : active raid5 sdc4[1] sda4[3] sdb4[2] 5860115712 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/3] [_UUU]
md1 : active raid10 sda2[0] sdd2[3] sdc2[2] sdb2[1] 1044480 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
md0 : active raid1 sda1[5] sdc1[3] sdd1[6] sdb1[4] 4190208 blocks super 1.2 [4/4] [UUUU]
unused devices: <none>
/var/log# mdadm --detail /dev/md126 /dev/md126: Version : 1.2 Creation Time : Fri Nov 1 10:17:34 2019 Raid Level : raid5 Array Size : 11706503424 (11164.19 GiB 11987.46 GB) Used Dev Size : 3902167808 (3721.40 GiB 3995.82 GB) Raid Devices : 4 Total Devices : 4 Persistence : Superblock is persistent
Update Time : Fri Nov 5 20:15:36 2021 State : clean Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0
Layout : left-symmetric Chunk Size : 64K
Consistency Policy : unknown
Name : 0e349ed8:Volume_Backup-0 (local to host 0e349ed8) UUID : a5655641:0de3a15d:04ae0e91:b294b7d0 Events : 235152
Number Major Minor RaidDevice State 5 8 3 0 active sync /dev/sda3 4 8 19 1 active sync /dev/sdb3 6 8 51 2 active sync /dev/sdd3 3 8 35 3 active sync /dev/sdc3
/dev/md127: Version : 1.2 Creation Time : Fri Nov 15 09:24:58 2019 Raid Level : raid5 Array Size : 5860115712 (5588.64 GiB 6000.76 GB) Used Dev Size : 1953371904 (1862.88 GiB 2000.25 GB) Raid Devices : 4 Total Devices : 3 Persistence : Superblock is persistent
Update Time : Fri Nov 5 20:15:55 2021 State : clean, degraded Active Devices : 3 Working Devices : 3 Failed Devices : 0 Spare Devices : 0
Layout : left-symmetric Chunk Size : 64K
Consistency Policy : unknown
Name : 0e349ed8:Volume_Backup-1 (local to host 0e349ed8) UUID : 31979138:f23cfef8:dca0bbed:4e1804e3 Events : 113565
Number Major Minor RaidDevice State - 0 0 0 removed 1 8 36 1 active sync /dev/sdc4 2 8 20 2 active sync /dev/sdb4 3 8 4 3 active sync /dev/sda4
I agree it doesn't look like it's expanding. First, make sure a 4th partition was created: fdisk -l /dev/sdd. You can also compare the size of the 4th partition to another drive's: fdisk -l /dev/sdc. If the partition is there and the right size, then the following should add it or give you an error message as to why it won't: mdadm /dev/md127 --add /dev/sdd4 --verbose.
If the partition isn't there, don't try to use fdisk to create it, it'll refuse to start it in the right place. I recommend you install and use parted for that.
The WD60EFAX drives use SMR technology. Several folks here have found they misbehave in OS-6 ReadyNAS. SMR drives have variable write speeds (sustained writes can result in glacial speeds).
Generally I don't recommend them for any NAS - not saying you should replace them, but I do suggest keeping an eye out for problems.
1. "SMR-Drives"--- I have them since almost 2 years now and yes, I am in the progress of replacing them step-by-step - the one I replaced was also an "SMR".
2. Is resync really running? Usually I see it in the /proc/mdstat. Any proposal where I can see if resync is running if it is not shown on the readynas itself, the web-interface or in the /proc/mdstat file?
2. Is resync really running? Usually I see it in the /proc/mdstat. Any proposal where I can see if resync is running if it is not shown on the readynas itself, the web-interface or in the /proc/mdstat file?
That's a good question. Usually it is shown on the volume page. Your mdstat post shows sdd is missing from md127 (but it is in the md126 raid group).
I agree it doesn't look like it's expanding. First, make sure a 4th partition was created: fdisk -l /dev/sdd. You can also compare the size of the 4th partition to another drive's: fdisk -l /dev/sdc. If the partition is there and the right size, then the following should add it or give you an error message as to why it won't: mdadm /dev/md127 --add /dev/sdd4 --verbose.
If the partition isn't there, don't try to use fdisk to create it, it'll refuse to start it in the right place. I recommend you install and use parted for that.
It was clear from the mdstat that the partition never got added to the volume, which would have then started the re-sync. The only question was why, and we still don't know. But I agree that manually doing so seems to have done the trick. But keep a lookout in case it fails somewhere along the way.
For whatever reason, the ReadyNASOS seems to increase the number of drives in an array before it adds a device to fill the empty slot. It is much more common to first add the device (so it becomes a spare), then change the number of devices (which will automatially start integrating the spare into the RAID).
Sandshark, I will follow, but for the time being things are running now as expected... Thanks again. Honnestly the RN104 is already a liittle bit older, and I am happy adding an 8TB drive is working at all... Latest next week resync shall be done.
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